NEW! UNIX Email Software Survey FAQ [Part 1 of 3]
Chris Lewis
Last-modified: Mon Feb 21 09:57:01 EST 2000
UNIX EMail Software - a Survey
Chris Lewis
cle...@ferret.ocunix.on.ca
[and a host of others - thanks]
Copyright 1991-1998, Chris Lewis
Redistribution for profit, or in altered content/format
prohibited without permission of the author.
Redistribution via printed book or CDROM expressly
prohibited without consent of the author. Any other
redistribution must include this copyright notice and
attribution.
Note to the patient readers who noticed that nothing has changed in this
FAQ since 1996...
Email systems have changed radically over the past few years, and I'm
beginning the daunting task of bringing this FAQ into the new world.
I'm planning a lot of changes:
- Adding POP/IMAP discussions, and common implementations
- Extensive coverage of anti-spam measures resources, and
packages.
- Updating recommendations to include things like the phase out
of UUCP, predominance of POP/SMTP/MIME etc., S/Mime, PGP
etc.
- Other suggestions?
I've started off the ball by mostly changes in the second and third parts:
- updated sendmail
- dropped IDA sendmail references.
- dropped EASE references
- begun the deprecation of obsolete solutions (UUCP, UUCP maps etc)
- added exim.
- added qmail.
| - updated MMDF
It would help a lot if anyone wanting to add a section on their favourite
email topic (UNIX please!) could write it and send a copy to me. I'll also
be dredging through my archives to find previous comments that haven't yet
been added.
Changes are marked with a preceding "|". You can skip to them
by typing g^| in (most) newsreaders.
Note: this FAQ has been formatted as a digest. Many newsreaders
can skip to each of the major subsections by pressing ^G.
Please direct comments or questions to mai...@ferret.ocunix.on.ca -
note Reply-to: line - automatic if you reply to this article.
Many changes made in the second and third parts.
------------------------------
Subject: Introduction
Configuring electronic mail systems can be quite a complicated
subject. Often far more complicated than, say, setting up
a Usenet news feed. This is because, unlike news, email is
expected to traverse multiple types of networks using their own
protocol, whereas, Usenet news tends to be a single protocol
supported by hook or by crook on different networks.
This document is intended for system administrators who need to
know how to set up their UNIX systems for email communication with
the outside world. It is intended for the email-naive SA
who gets more than a little confused by the acronyms, RFC's and
plethora of software.
This is intended to be a general survey of the software available,
so I won't spend too much time on some of the details. Most of
the available software comes with documentation that can
explain things much better than I can.
Additional detail can be obtained from several sources, such as:
Quarterman, John S.: "The Matrix -- Computer Networks
and Conferencing Systems Worldwide", Digital Press 1990,
(Order No. EY-C176E-DP), ISBN 1-55558-033-5.
Adams, Rick and Frey, Donnalyn: !%@:: A Directory of Mail
Addressing and Networks, 3rd Ed., O'Reilly & Associates 1993,
Provides a good reference for people seeking information
on how to access the various email networks.
ISBN 1-56592-031-7.
Kehoe, Brendan P.: Zen and the Art of the Internet: A
Beginner's Guide, Second Edition, Prentice Hall 1992,
ISBN 0-13-010778-6. Edition 1 is available via FTP on
cs.widener.edu in the tar file zen-1.0.tar.Z. [I think]
Krol, Ed: The Whole Internet: User's Guide & Catalog.
First edition, O'Reilly & Associates Sept. 1992.
ISBN: 1-56592-025-2. Very good introduction to
the Internet, history, facilities, uses, services,
etc. I learned a lot.
Albitz, Paul & Liu, Cricket: DNS and BIND, First edition,
O'Reilly & Associates, October 1992. ISBN: 0-56592-010-4.
Describes in great detail everything from what a domain
is, to how to install and configure BIND. A *MUST* for
people setting up large networks, or connecting
machines to the Internet. It has become mandatory reading
for network administrators in a large corporation for
good reason.
Costales, Bryan and Allman, Eric and Rickert, Neil: Sendmail.
O'Reilly & Associates, Nov (?) 1993. ISBN 1-56592-056-2
(ISBN from galley proof, which I've had a preview of).
An absolute necessity for anyone diving into the configuration
of sendmail. The material is presented in a very clear
form, and is quite exhaustive in its coverage. Perhaps a bit
too wordy and overlong, but that's a more than welcome contrast
to previous documentation (or lack thereof) on sendmail.
Further, this is primarily oriented towards UNIX email systems.
This is unfortunate, because it would be nice to have a general
document covering email in all of its forms. However, each
operating system tends to have radically different email mechanisms,
so it would be difficult to do justice to any other environment.
It seems more useful to cover one environment well here, and have
companion documents for other environments. Speaking of which,
why hasn't anybody else stepped in to do FAQs on other environments?
Like DOS, Mac etc.
And finally, this document is not intended to be pedantically
correct. Knowledgeable readers will know that I'm glossing
over a lot of detail, and absolute precision has been balanced
against readability and effectiveness in helping people get
going.
------------------------------
Subject: Layout
This FAQ is laid out in the following sections:
+ An overview of how mail systems go together.
+ A glossary of the important terms to know.
+ A list of general do's and don'ts of mail systems.
+ Configuration Issues
+ Several suggested mail configurations.
+ General overviews of specific software.
------------------------------
Subject: Electronic mail - A General Overview of Structure
Electronic mail generally consists of three basic pieces:
1) The link level transport - which could be
UUCP, TCP/IP, or a host of others. We'll call
this the "transport medium" (TM)
2) the "Mail Transport Agent" (MTA) which is responsible for
transporting mail from source to destination, possibly
transforming protocols, addresses, and routing the mail.
The MTA often has several components:
- Routing mechanisms
- Local delivery agent (LDA)
- Remote delivery agent
Many MTA's have all of these components, but some
do not. In other cases, it is possible to replace
certain components for increased functionality.
3) The "User Agent" (UA) is the user interface -
the software that the user uses to read his mail,
sort things around in folders, and send mail.
Sometimes called "Mail User Agent" (MUA).
------------------------------
Subject: Glossary
Rather than alphabetic, this glossary tends to group terms
referring to similar functionality together.
Transport Medium:
UUCP (Unix to Unix Copy Program):
Back in the mists of time, UNIX systems communicated only
over RS232 serial lines, usually over modems. UUCP is a
suite of programs developed back in the early 70's to
provide this communications link. All that UUCP does is
transfer files from one system to another. There is an
additional mechanism where one system can direct the
destination system to run a file through a specific program.
Electronic mail in UUCP is simply requesting the destination
machine to run "mail" on a data file.
UUCP communicates by means of "protocols", the most common
being "g", a method for transmission of data over telephone
lines and ensuring that the data is not corrupted. There
are several other protocols, none universally available,
and most oriented towards communication media other than
telephone voice lines (such as dialup X.25, PAD X.25, or
LAN connects).
UUCP operates over fixed system-to-system links, so sending
mail from one system to another often has to traverse
other intermediate systems.
| If you like source, Taylor UUCP is an excellent full-featured
| implementation of UUCP, with many enhancements to deal with higher
| modem speeds. It is FreeWARE.
| UUCP mail protocols (bang paths) are now being deprecated, because
| DNS and MX etc., are making it wholly unnecessary.
TCP/IP (Transmission Control Protocol/Internet Protocol):
TCP/IP is a protocol that allows any system on a network to
talk "directly" to any other, by passing packets of
information back and forth. TCP/IP (and its later relative
OSI) is usually used over networks built on top of Ethernet,
Token-Ring, Starlan and other LANS.
SMTP:
Or, "Simple Mail Transfer Protocol", is the communications
protocol used most commonly over TCP/IP links in UNIX
environments for mail. SMTP usually operates directly between
the source and destination machines, so intermediate machines
don't get involved (except for gateways, see below). SMTP
is usually part of the MTA.
SLIP (Serial Line Internet Protocol):
SLIP is an implementation of TCP/IP designed for use over
RS232 serial lines (ie: modems). The other difference is
that some SLIP implementations have the ability to "dial the
phone" to make a connection for a specific transfer, whereas
LAN TCP/IP is physically continuously connected. You'd also
need TCP/IP to run a SMTP mail connection.
PPP (Point-to-Point Protocol):
A successor to SLIP.
X.25/X.29:
X.25 is a packet switched data network which is usually
half-duplex. In this context, it's really an alternative
to dialup over voice telephone lines with modems. X.25
is available in several "flavours", either direct X.25
trunk connects over leased lines, through "PAD" interfaces,
or by ordinary dialup modem access to X.25 "ports".
To be useable in the context of mail transfers, you also
have to use a file transfer protocol/mechanism of some
sort on top of X.25. The most common being UUCP "f" protocol
(through PADS or dialup), or "x" with direct X.25 connects.
Whether you use X.25 or phones plus modems depends on a number
of factors - usually the determining factor is cost. In North
America, high speed modems (eg: 9600 baud and above) over telephone
lines tends to be less expensive. However, Europe's really
wierd phone system structure usually makes X.25 more cost-effective,
and therefore, X.25 use in UNIX mail systems is much more common
in Europe than North America.
X.29 is the command set used to configure and establish
X.25 connections when you're using asynchronous connections
to a PAD.
Networks:
Internet:
An "internet" is a network comprised of computers that talk
to each other using TCP/IP, and usually SMTP for mail.
The "Internet" is a vast network of hundreds of thousands of
machines using SMTP protocol mail, communicating with
each other over relatively high speed lines. But not all
"internets" are connected to *the* Internet.
The Internet grew out of a US government funded project in
inter-computer communications that grew into an enormous network
of systems.
| One of the principal characteristics of this network is that
machines are addressed by domain names which identify the
destination, rather than addresses that are constructed out
of the route from machine-to-machine-to-machine.
UUCP Network:
The UUCP network is that set of machines that talk to each other
via UUCP. Sending mail through this network requires that the sender
know the network topology of UUCP links, and specify a path from one
machine to the next. (There are, of course, ways around this.
See the section on "do's and don'ts".)
Mail addresses:
Addresses:
An email address is a method of specifying a given person on
a specific machine. There are scads of conventions, usually
determined by the presence of "@"'s, "!"'s and other special
characters in the name. An address usually consists of
two parts: a userid/name and a machine specification.
A Domain address usually looks like:
userid@domain-address
Whereas a UUCP address usually looks like:
siteA!siteB!siteC!userid
Domain Addresses:
Domains are a way of uniquely specifying a destination.
Much like a postal address, a domain specifies a set of
progressively more restrictive "domains" of the potential
address space. It would perhaps be illustrative to give an
example:
cle...@ferret.marketing.fooinc.com
You read these things right to left: "com" means the
commercial domain. "fooinc" is the name of an organization
within the commercial domain. "Marketing" is the name of a
suborganization within fooinc, and ferret gives the name of
a machine (usually). Domains can have any number of levels.
The top level domain (com in the above example) has many
possible values. In the United States, "com", "mil", "edu",
and "gov" are fairly standard. Elsewhere, the top level
domain tends to be a country code, the second level tends to
be a province or state, OR a classification like "edu" or "ac"
for academic (such as ac.jp, go.jp, ac.uk, edu.au, etc)
and the third an organization. But, for example, there are
many .com and .edu sites in Canada and other countries.
FQDN
A fully-qualified-domain-name (FQDN) has a entry for each
level of the domain, from individual machine to top-level
domain. In many cases, an organization has implemented an
organizational "gateway" at a higher level of domain, so
that people from outside don't have to specify FQDN's to get
to a specific person. In the above example, for instance,
"fooinc.com" may be sufficient to get to anyone inside
fooinc, and "ferret.marketing" may not be necessary.
On the other hand, people sometimes leave out the higher
levels of the address, as in "ferret.marketing".
This is a bad idea - because if the mail is cc'd out of the
organization, chances are the external recipient cannot reply,
because "ferret.marketing" is incomplete. So use addresses
that are specified sufficiently for external users to use.
(fooinc.com if a organizational gateway is used, the whole
ferret.marketing.fooinc.com if not)
NIC
Internet TOP-LEVEL domains (edu, com, gov, mil) are controlled
by a single organization, the NIC (internic.net). An organization
"gets a piece" of the namespace by registering with the NIC, and
then they are free to administer their own namespace (everything
under fooinc.com) as they choose. The same is true for foreign
countries; Once they have their top-level domain (usually the
two-letter ISO country code) registered with the NIC, they do
the rest, and divide it as they see fit.
In contrast, on UUCPnet, all machine names everywhere share a
single flat namespace. So it is important to choose a name
that has not been used before. (See do's and don'ts). This is
why FQDN's help. We can tell the difference between
ferret.fooinc.com and ferret.blah.edu by their full names.
(Instead of UUCP paths which may turn out to be wrong, and
autorouting will probably send the mail to the wrong machine)
MX record:
A non-SMTP/Internet site that wishes to register on the Internet
will need to get a "nearby" Internet site to set up a MX
record for them. An MX record is essentially a domain-server
database record that (effectively) registers your domain name
on the Internet, and indicates that the Internet site knows
how to forward mail to you. Usually via some non-SMTP/Internet
route, such as UUCP. You can get an MX record for one site, or
a "wildcard" MX record so that you can have your own subdomains.
Bang-Paths:
With UUCP mail, the MTA has to specify a route to get from one
machine to another. "A!B!C!userid" means go to machine A,
then B, then C, then user "userid" on C. You should strive,
however, for a MUA that allows you to use domain addressing,
and let the MTA figure out the bang routing as appropriate.
Miscellaneous:
Gateways:
There are several meanings of this term, only three are relevant
here.
The first is a mechanism for getting from one network to another
network that uses different protocols.
The second is a mechanism for getting from one logical (often
organizational) network to another using the same protocol.
Often for example, there will be a LAN in one department of
an organization, and one machine in the LAN has the connection
to another LAN in another department. This means that mail from
one LAN to the other has to pass thru the gateway machine.
Another form, which we'll mention later is that of mail to
news gatewaying.
Routers:
There are several definitions, but the most important is that
part of the TA that figures out how to send a message to
a given machine. This often uses a database that provides
routes from one machine to the other machines on the network.
Smarthost:
In many cases, your machine won't know how to get to a specific
destination. You can usually set up your mail system to send mail,
that it doesn't know how to deliver, to a machine that is more
likely to.
RFC's:
A set of documents that include formal descriptions of mail
formats used on the Internet, and are adhered to by many
non-Internet systems. More specifically, in the "worldnet"
of Usenet, Internet and UUCP, the RFC's set the standards
for mail exchange. RFC822, 1123 and 976 are the most important
for Internet/UUCP mail.
It should be pointed out, however, that there are some
regions where the RFC's are not entirely respected. For example,
the British academic email networks (JANET) uses domains, but
they're specified backwards (they drive on the wrong side of
the road too ;-).
MIME:
Mime is the official proposed standard format for multimedia Internet
mail encapsulated inside standard Internet RFC 822 messages. Facilities
include sending multiple objects in a single message, character sets
other than US-Ascii, multi-font text messages, non-textual material
such as images and audio fragments, and other extensions. For an
overview of Mime, see ftp.uu.net:networking/mail/metamail/MIME-overview.txt.Z.
The defining document is Internet RFC 1341: N Borenstein & N Freed,
``Mime (Multipurpose Internet Mail Extensions) mechanisms for specifying
and describing the format of Internet message bodies'' (June 1992).
Also see RFC 1344: N Borenstein, ``Implications of Mime for Internet
mail gateways'' (June 1992).
RFC1341 and 1342 have since been superceded by RFC 1521 and 1522.
Mime covers only message bodies, not message headers; to see how to
represent non-Ascii characters in message headers, see Internet
RFC 1342: K Moore, ``Representation of non-Ascii text in Internet
message headers'' (June 1992).
X.400:
A CCITT standard for email formats, more or less an alternative
to RFC 822/976/1123. This format will probably start taking over
from RFC 822/976/1123 mail. It is likely to (already has?) become an
ISO/IEEE standard along with OSI etc.
"The Maps":
A set of files describing machine-to-machine links distributed
over Usenet in the group comp.mail.maps. These are usually posted
on a monthly schedule, and can be automatically received and
transformed into a routing database that describes the "optimal"
route to each machine. These are operated by the "UUCP Mapping
Project". See the README posted along with the maps for
more details.
Aliases:
Aliases are a mechanism by which you can specify the destination
for mail on your machine. Through the use of aliases you can
redirect mail to "virtual userids". For example, you should
have a mail destination on your machine called "postmaster", which
is aliased to send the mail to the System Administrator (ie: you
probably). Aliasing often also permits you to send mail to groups
of users (not necessarily on the same machine as you) pipelines of
commands or to specific files.
Mailing lists:
Are similar to Usenet newsgroups. They are usually aliases
pointing to groups of users, and allow mail to be sent to the
whole group at once. Mailing lists are set up to carry certain
subjects. The difference between a mailing list and a Usenet
newsgroup is that the messages are sent by mail, probably as
a copy to each recipient, rather than broadcast.
------------------------------
Subject: Do's and Don'ts:
1) Register a domain name. Even on UUCP, where <machine>.UUCP is often
used as a kludge, it is MUCH preferred that you obtain a real
domain address. If you are directly connecting to the Internet,
you will get one as part of your registration with the NIC.
If you aren't connecting directly to the Internet, obtaining a
registration will usually require you finding a nearby friendly
Internet site willing to act as a mail forwarder to you from
the Internet - the site that will set up a "MX record" for you.
Many sites will do this for you for free, and several of the
commercial email services (eg: uunet) will do it for you for a
nominal charge (without requiring you buy the rest of their
services).
There are occasions where you can join what is called a "domain
park". These are most often small regional groups of systems that
have gotten one of their number properly registered as a domain,
and provides forwarding services out to other systems. For
example, in my address "ferret.ocunix.on.ca", "ocunix.on.ca"
is a domain park made up of the Ottawa-Carleton UNIX User's Group,
one of the other machines in the group provides a gateway between
our systems and the Internet.
2) If your machine is going to "speak" UUCP to the outside world,
choose a unique UUCP name. You can find out whether a name you
want is taken by consulting the UUCP maps. Or by asking someone
else who's using them.
3) Register your machine with the UUCP Mapping Project if you're going
to use UUCP. Information on how to do this is included in the
monthly maps postings in the file "README". This is usually only
required when your machine talks UUCP to the outside world, or when
other machines have to address you by your UUCP name. If you don't
do this, somone else may choose the same name, and gross confusion
will arise when smart routers won't be able to tell whether to send
a piece of mail to you, or your doppelganger[s]. If you register
with the UUCP Mapping Project, you have prior use, and people who
choose the same name afterwards will be told to get a new one.
If you're "behind" an organizational gateway, don't do this.
(Your organizational gateway is the thing that needs to be
registered)
If you do fill in a map, please take the time to fill it in
carefully, giving contact people and phone numbers. Just in
case your machine goes crazy and starts doing something nasty.
Note expecially the latitude and longitude. Get it right,
or omit it. Brian Reid gets really annoyed with sites that
are half a world away from where they really are.
4) If you're going to be setting up multiple machines, have only
one or two connections to the outside world.
5) Install a mail system that understands domain addressing, even
if you aren't registered. (In fact, all of the suggested
configurations in this FAQ do)
6) *Never* use UUCP bang-routing with the MUA if you can possibly
avoid it - each of the suggested mail configurations provide
mechanisms where you, the user, do not have to specify routes
to the MUA - you can specify domains, and the TA will do the
routing (possibly bang-routing) for you.
Important: many mailers that understand UUCP attempt to be
pedantically "UUCPish" in the construction of headers, such
as generating "bang routes" in From:/To: etc. lines. Which,
given that the whole "mail network" is generally converging on
more Internet-like standards, and that even UUCP sites are
using fully domain-capable mailers, is a big mistake. RFC976
attempts to codify a "meta standard" that allows the coexistance
of RFC822 (Internet mail) with UUCP-based networks. What
this means is, essentially, that headers are formed in the
SMTP form, even if the transport will be via UUCP. Unfortunately,
however, many mailers insist on "UUCP-izing" perfectly useable
Internet/domain headers. "Fixing" them to prevent this is sometimes
difficult. Sendmail is almost always a problem in this regard.
7) Find a friendly neighboring SA to help. A SA who has already
operating mail in your area will help smooth over the regional
"gotchas" that are bound to crop-up. And advise you on the
right software to use, where to obtain it, and how to install it.
8) Do NOT use "any old" Map unpacking program. Most available
map unpacking programs automatically run the shell (or shar)
to unpack map articles. Since it is trivially easy to forge
map articles, using this type of unpacking program can
easily let very destructive trojan horse or virus programs
into your machine.
The two specific map unpackers described in this FAQ are known
to be secure from such attacks. Do not run any other unpacker
unless you are aware of the issues and can inspect the code for
such vulnerabilities. [If you know of other "secure" map
unpackers that are generally available, please let me know]
9) If the people on your site, or small network, receive mailing
lists, it's often a good idea to gateway them to news:
Netnews often performs many of the same services as email.
The primary difference is that messages are centrally stored,
rather than delivered to individual's mailboxes, and that
distribution looks more like a broadcast then a set of point-to-point
communications. This means usually means that news can handle more
volume, more efficiently, then email can.
Because of the differences (and also the similarities) people often
want to tie news and mail together. This is known as "gatewaying."
For example, a small software development site might subscribe to the
X Windows mailing list. Rather than have (say) eight copies of each
mail message sent to their host, they would rather have it stored as a
local newsgroup that everyone in the company can read, and which can
be centrally archived. This is a typical use of a "mail to news"
gateway. When a user makes a posting to this local group the article
should be sent back out to the mailing list; this is a typical use of
a "news to mail" gateway.
On a larger scale, the "inet" groups are bi-directional gateways of
Internet mailing lists. Within mainstream Usenet, many popular
groups such as comp.windows.x, comp.protocols.tcp-ip, comp.unix.wizards,
and so on, are gatewayed to mailing lists and back.
Many subtle issues often come up when gatewaying mail and news, so
unless you are experienced you should use one of the already-available
packages for your local organization. For example, you probably do not
want to write a brand-new Perl script and create a new "inet" newsgroup.
The C News distribution includes some basic gateway tools in the
contrib/nntpmail directory. Many people use Rich $alz's "newsgate"
package that appeared in comp.sources.unix Volume 24; it includes
discussion of some of the more subtle issues that come up.
Before starting a mailing list gateway, apart from the technical aspect
of the job you should also be aware of one important point: mailing-lists
are considered private, whereas newsgroups are public.
One can know who gets a list, but not who reads the group. It is always
wise to get the authorization of the mailing-list manager and of the readers
before creating a mail/news gateway.
10) If you're connecting to the Internet, or are setting up a large local
internet, you really should get a copy of the DNS and BIND book mentioned
in the bibliography.
Chris Lewis
Last-modified: Mon Feb 21 09:57:37 EST 2000
UNIX EMail Software - a Survey
Chris Lewis
cle...@ferret.ocunix.on.ca
[and a host of others - thanks]
Copyright 1991, 1992, 1993, Chris Lewis
Redistribution for profit, or in altered content/format
prohibited without permission of the author.
Redistribution via printed book or CDROM expressly
prohibited without consent of the author. Any other
redistribution must include this copyright notice and
attribution.
Mailshield Author: Lyris Technologies http://www.lyristechnologies.com
[Watch this space, see http://www.mailshield.com]
Exim* Author: Philip Hazel (ph...@cus.cam.ac.uk)
[Author note: Exim is very highly regarded in the industry, and it,
along with qmail, are the most frequently recommended replacements
for sendmail on UNIX.]
Exim is a mail transport agent (MTA) developed at the University
of Cambridge for use on Unix systems connected to the Internet.
It is freely available under the terms of the GNU General Public
Licence. In style it is similar to Smail 3, but its facilities
are more extensive, and in particular it has options for
verifying incoming sender and recipient addresses, for refusing
mail from specified hosts, networks, or senders, and for
controlling mail relaying.
Exim is intended for use as an Internet mailer, and therefore
handles addresses in RFC 822 domain format only. It cannot handle
'bang paths', though simple two-component bang paths can be
converted by a straightforward rewriting configuration. However,
there is no problem in interfacing Exim to UUCP systems, provided
they use domain-style addressing.
Exim is in production use at quite a few sites, some of which
move hundreds of thousands of messages per day.
The following operating systems are currently supported: AIX, BSDI, DGUX,
FreeBSD, HI-OSF (Hitachi), HP-UX, IRIX, Linux, MIPS RISCOS, NetBSD,
OpenBSD, DEC OSF1 (aka Digital UNIX), SCO, SCO SVR4.2 (aka UNIX-SV),
SunOS4, SunOS5 (Solaris 2), Ultrix, and Unixware.
Further information can be obtained from the Exim web sites:
http://www.exim.org (main site, in the UK)
http://www.us.exim.org (a mirror in the USA)
|qmail: Author Daniel Bernstein <d...@pobox.com>
|
| [Ed note: Qmail, along with Exim, is the most often recommended
| sendmail replacement. Qmail is capable of handling very high mail
| volumes. Qmail is one of the few mailers capable of integrating
| spam filters directly, however, given how this is done, qmail probably
| could not match the volumes of, say, Mailshield - which was designed
| for the purpose of filtering spam from the beginning.]
|
| Web page: http://www.qmail.org
| also: ftp://koobera.math.uic.edu/www/qmail.html
|
| Download:
| ftp://koobera.math.uic.edu/pub/software/qmail-1.03.tar.gz
| ftp://koobera.math.uic.edu/www/software/dot-forward-0.71.tar.gz
| ftp://koobera.math.uic.edu/www/software/fastforward-0.51.tar.gz
| ftp://koobera.math.uic.edu/www/software/ucspi-tcp-0.84.tar.gz
|
| RPMs: ftp://moni.msci.memphis.edu/pub/qmail
|
| Lists: mailto:qmail...@list.cr.yp.to
| mailto:qmailanno...@list.cr.yp.to
|
| qmail is an MTA for UNIX and UNIX-like systems (including FreeBSD,
| Linux, SunOS, Solaris, HP/UX, AIX, amongst others). It was written by
| Dan Bernstein to overcome the limitations of and flaws in sendmail, and
| to demonstrate by example that there are better ways of doing some
| things (see Maildirs below).
|
| * qmail is Modular
|
| qmail follows the UNIX philosophy of combining small single-purpose
| tools together. Instead of being one enormous setuid-root binary,
| qmail comprises a suite of small programs, each of which does one
| particular job. This makes qmail flexible, allowing substitutions
| to be made for individual parts of the system according to one's
| requirements.
|
| Substituting qmail-qmqpc for qmail-queue, for example, turns qmail
| into "mini-qmail" (see below). For another example, all user
| authentication in the POP3 server is done by calling a separate
| external utility program, checkpassword, so changing the
| authentication scheme merely involves replacing that program.
|
| Even qmail's configuration is modular. qmail doesn't have large
| monolithic configuration files with complex structures, that have to
| be read and parsed every time that a new mail process is created,
| only to have 70% or more of that information remain unused because
| it is irrelevant to the task at hand. qmail's configuration
| comprises individual files in /var/qmail/control, each file having a
| single job. The names of the local domains are listed, one per
| line, in /var/qmail/control/locals, for example. Many configuration
| tasks (and FAQ answers!) are, as a result of this philosophy,
| one-liners involving `echo' and `cat'.
|
| * qmail is Secure
|
| qmail was designed to be secure. Not only does the mail system not
| trust the outside world, but different modules in the mail system
| don't even trust one another. Different parts of the mail system
| run under different non-privileged UIDs ("qmaild", "qmailr",
| "qmailq", &c.). So, for example, even if the SMTP server
| (qmail-smtpd, which runs as user "qmailr") were compromised, the
| rest of the system will not be.
|
| qmail has only one setuid binary, qmail-queue which is setuid to one
| of the qmail user IDs, not root. qmail has only two programs that
| run as root, qmail-start which spawns the other daemon processes
| under the correct UIDs and qmail-lspawn which spawns the local
| delivery program qmail-local under the UID and GID of the user being
| delivered to. Neither program writes to any files or spawns any
| program under the root user ID.
|
| And, of course, qmail doesn't treat root as a "real" user, and so
| never delivers mail as root.
|
| * qmail provides a flexible aliasing/forwarding mechanism, qmail files
| qmail supports /etc/aliases and .forward with its fastforward and
| dot-forward packages. However, it is a testament to the power and
| versatility of qmail's own "native" aliasing and forwarding
| mechanism that both are merely plug-ins that run off it.
|
| With qmail, each user controls all local parts that begin with the
| user's username, allowing each user to have an unlimited number of
| different local parts. Delivery to each local part is (optionally)
| controlled by a separate .qmail-* file in the user's home directory
uumail:
Uumail is a very old and obsolete precursor to smail 2.5. Included
here only because I know that uumail sites still exist. You
should not install uumail in new configurations, and existing
uumail sites should convert to something more modern.
smail 2.5: author The UUCP Mapping Project
[Not recommended for general use now. UUCP is very little used.]
Smail 2.5 is a small, simple and hard-coded rule MTA for use on
UUCP networks. It understands RFC compliant headers, will
generate RFC compliant Internet-style headers, can
use domains, aliases, a pathalias UUCP routing database, and
is very simple to install. For full functionality, you will
also want pathalias and a map unpacker. The one thing
it cannot do by itself is mail-to-pipe and mail-to-file aliasing.
For that, you need Zeeff's lmail, deliver or procmail.
Smail 2.5 has the capability of coalescing addresses into single
UUCP transfers, and knows how to query UUCP for the names
of UUCP neighbors, and autoroute if necessary.
Smail 2.5 has a few bugs that are (usually) pretty rarely seen
in operation. There have been a number of patches posted for it,
but it is recommended that you do not apply them - some were
ill-conceived, buggy in their own right, or conflicting with others.
The only patches that I feel safe in recommending is Chip
Salzenberg's patches for use with Xenix MICNET - which are
unnecessary unless you are in the unfortunate position of having
to actually *use* MICNET. Chip Salzenberg's "deliver" package
(see below) combined with "smail-deliver.pch" from comp.sources.unix,
volume 25 issue 107, makes the MICNET modifications to smail
itself unnecessary.
In particular, do not apply the "mail-to-pipe/file" patches that
float around for smail 2.5. These are a major security hole.
Smail 2.5 can also be used with sendmail as a UUCP router.
Smail 2.5 was posted in comp.sources.unix in 1987, volume 11
with archive name "smail3" (but it isn't the same thing as
smail 3 below).
lmail: Author Jon Zeeff <ze...@b-tech.ann-arbor.mi.us, ze...@ais.org>
When you install smail 2.5, you link the original /bin/mail (binmail
above) to /bin/lmail to perform the task of actually delivering the
mail to the user's mailbox (LDA).
Since smail 2.5 was not capable of doing mail-to-pipe and mail-to-file
aliasing, Jon Zeeff wrote a replacement lmail that implemented
these (along with user mailbox delivery).
Jon's program is okay for casual use, but has some pretty serious
bugs. Fixed versions are available, but you're probably better
off installing deliver or procmail.
smail 3: Author Ronald S. Karr* <tr...@veritas.com> and Landon Curt Noll.
Smail3.x is a domain-capable mail router and delivery program that
works in the UUCP zone and on the Internet and that is capable of
gatewaying between the two. It was written primarily by me (Ronald
S. Karr) and Landon Curt Noll, with the blessings of the original
Smail1 and Smail2 authors.
Smail3 supports SMTP, UUCP mail, alias files, .forward files, mailing
list directories, pathalias files, /etc/hosts files, the domain name
system, and can also query uucp for neighboring sites, automatically.
It also supports use of encapsulated SMTP commands for delivery over
UUCP connections, which allows batching of multiple messages into a
single UUCP transaction, and allows many addresses to be passed with a
single message transfer, which can greatly decrease the traffic
generated for large mailing lists. It is also very simple to configure
with a reasonable certainty of correctness.
Smail3 includes pathalias and a reliable map unpacker.
Rather than using configuration files to resolve addresses based on
their syntax, ala sendmail, Smail3 uses a database metaphore for
resolving addresses based on their contents. The set of methods that
Smail3 uses for resolving local addresses and hosts is configurable and
extensible. Smail3's methods for parsing addresses are not
configurable. It is the opinion of the authors that addressing on the
Internet and in the UUCP zone has become sufficiently standardized that
attempts to allow configurability in this area are now a hindrance to
the correct working of the network.
Questions related to Smail3 are usually discussed in comp.mail.smail.
There are also two discussion mailing lists. To join the mailing
lists, send mail to:
smail3-use...@cs.athabascau.ca
The current release of Smail3 is 3.3.x, and can be found on uunet,
in the directory /archive/networking/mail/smail/smail-3.1.29.1.tar.Z.
Smail 3 is covered under the GPL (if it matters)
sendmail: Original author Eric Allman
Sendmail is the granddaddy of all intelligent MTA's. It can do just
about anything. It's main problem is that it can do just about
anything. Modification of sendmail's configuration tables (which is
necessary with most vendor-supplied versions) is NOT for novices.
The language of the sendmail.cf is cryptic, but that isn't really
the problem. The problem is that it's extremely difficult
to know when the rules you are implementing are the right thing--
many sendmail configurations do slightly buggy, or even extremely
buggy, or illegal things. Default configurations and minimal changing
is the approach to take. The Sendmail 8.9 configuration environment
is recommended.
Worse, every vendor's version of sendmail is different, and many
of their sendmail.cf's don't work at all. HPUX is one example
of where the sendmail.cf is actually pretty sane. HP is to
be congratulated. On the other hand, some vendors, who shall
remain nameless, can't even get their sendmail to deliver to local
users, let alone get their sendmail to speak SMTP on a LAN.
The major problem with sendmail is that it tries to do too many
things. Rather than confining itself to handling local mail, and
simply routing external mail and leaving transport-specific
format/standards conversions to transport software, it attempts
(nay virually *insists*) that you have to do all of the
format/standards conversions for different transports all at once.
Which results in configuration files that are veritable nightmares
to maintain. And that many sendmail.cf files depend on out-of-date
standards for different transports, rather than trying to unify
them (as in RFC976).
Indeed, while common wisdom and practice mandates that MTAs don't
rewrite headers, sendmail makes it extremely difficult to *not*
rewrite headers. Which results in many major systems attempting to
"be nice", yet, totally scramble return addresses and the like.
There are several different sendmail lineages in the world but they
seem to be coming together now with Eric Allman's work creating
sendmail V8.x. Sendmail V8.1 was shipped with BSD 4.4 UNIX.
It is strongly recommended that anyone contemplating running sendmail
upgrade to at least 8.9.x (see www.sendmail.org), which has a number
of serious security problems fixed, or at least configurable w.r.t.
email spam. Ie: anti-relay, HELO overflow etc.
Another point to remember is that sendmail, historically, has been
where a large number of severe security holes have been found. From
the infamous RTM Internet Worm, to the latest ones "CERT"d in
witthin the past few months. Indeed, if your application is
security-critical, I recommend that you should *not* use sendmail on
your security-critical systems, such as your firewalls.
Unless your vendor has provided sendmail 8.9 or better, do not expose
it to the Internet. In particular, SunOS and up to recent Solaris are
extremely susceptable to abuse, _are_ being abused, and cannot be fixed
without upgrading. The latest Solaris sendmail patch resolves these
problems.
Administrators wishing something easier to configure than sendmail,
particularly with the addition of filtering rules, are best advised
to consider using qmail, exim instead, or, using mailshield SMTP
relaying to stand in "front" of sendmail.
Theoretically, all of these problems have been removed from sendmail
8.6.5 (now 8.9) or later, but, there's bound to be more found. While
some of this can be due to the much larger installed base of sendmail,
other mailers with improved function partitioning (such as the
channel-oriented MMDF or PP) will usually be inherently more secure.
I am being harsh on sendmail - sendmail programming is, after all, a
good source of revenue for consultants ;-) But, if you obtain a good
sendmail 8.9.x, or are willing to spend the time to learn it,
sendmail will do what you want. Well. Don't, however, even think
of playing with the configuration files without a copy of the
Sendmail book by Costales, Allman and Rickert mentioned in the book
list above. It is *absolutely* essential.
Sendmail is discussed in comp.mail.sendmail.
ZMailer: Original author Rayan Zachariassen* <ra...@cs.toronto.edu>
Current author Matti Aarnio <m...@nic.funet.fi>
ZMailer is intended for gateways or mail servers or other large site
environments that have extreme demands on the abilities of the mailer.
Code and Design features:
+ Strong limits on host impact.
+ Secure design (and hopefully implementation).
+ Natural fit for client/server environments.
+ Extremely customizable configuration mechanism.
+ Flexible database interface with support for: sorted files, unsorted
files, dbm, ndbm, gdbm, nis (yellow pages), dns (BIND resolver),
/etc/hosts file, and in-core data.
+ Efficient message queue management.
+ Fast binary-transparent SMTP server and client.
+ MIME-facilities for message transport.
+ Low-technology implementation, with high-tech options for performance.
Default configuration file features:
+ Default configuration will work for most sites.
+ Network protocol support for: smtp, uucp, bitnet, mail to news.
+ An easy way of overriding any external routing information.
+ Automatic handling of mailing lists.
It is available by anonymous FTP from:
ftp://ftp.funet.fi/pub/unix/mail/zmailer/ (Mr. Aarnio's versions)
Alternate (some of them old) versions:
ftp://ftp.cs.toronto.edu/pub/edwin/zmailer2.2.e4.tar.Z
ftp://ftp.cs.toronto.edu/pub/zmailer.tar.Z
MMDF: [reviewed by I.Sp...@gdt.bath.ac.uk, updated by Randall Atkinson
2000/02/21]
MMDF is a MTA. It works on the principle that you have communications
channels, both incoming and outgoing, and it arranges for messages to
pass between them.
Strong points include:
* Ability to turn up and down debugging level on the fly
* Very strong on authentication, and permission checking.
* Can block mail based on who it came from, how it got there,
who it is going to.
It is older than sendmail, simpler than sendmail, and it is a great
pity that it was not shipped as standard instead of sendmail.
[MMDF is standard on some systems - primarily SCO UNIX.]
It has one major advantage to people in the UK, in that it knows how to
handle mail addresses in our 'correct' format (Most significant part first,
e.g. net.uu.uunet), as well as the thing the rest of the world uses :-) :-)
| A mailing list for MMDF discussion is at mm...@skymaster.c2-tech.com
| requests for addition to the list to mmdf2-...@skymaster.c2-tech.com.
|
| MMDF is being maintained at the University Kaisers-Lauten in
| Germany:
|
| http://www.mathematik.uni-kl.de/ftp/pub/Sources/mail+news/mmdf and
| ftp://www.mathematik.uni-kl.de/pub/Sources/mail+news/mmdf
|
| The MMDF Users Group has a web site at http://www.mmdf.org
PP: Author University College London
PP is a Message Transfer Agent, intended for high volume message
switching, protocol conversion, and format conversion. It is targeted for
use in an operational environment, but may also be useful for investigating
Message related applications. Good management features are a major
aspect of this system. PP supports the 1984 and 1988 versions of the
CCITT X.400 / ISO 10021 services and protocols. Many existing RFC 822
based protocols are supported, along with RFC 1148 conversion to X.400.
PP is an appropriate replacement for MMDF or Sendmail, and also supports
SMTP and UUCP mail.
For more information contact: sup...@xtel.co.uk or xt...@cs.nott.ac.uk
The latest version is PP-6.0, which was posted in comp.sources.misc,
volume 27.
[Ed note:]
PP is usually used in combination with the ISODE package, which
also provides copious documentation for PP. PP itself is
"freeware", but ISODE and the PP documentation is not - site
licenses are rather pricy. PP is *very* large, and has quite a
number of more esoteric functions, such as FAX transmission using
the appropriate modems. PP is ideal for large organizations with
demanding email requirements (eg: 100s of machines and 1000s of
users), where PP would be used as "backbone mail servers", and something
simpler on the "client" computers. It does have _substantial_
learning and support requirements, and is *not* suitable for smaller
installations. It does, however, shine in large production environments,
where policy-based routing, high levels of security, or extensive
gatewaying to different transports is required.
SVR4 mail: Author AT&T (description written by Tony Hansen,
han...@pegasus.att.com)
The System V Release 4 mail system is a domain-capable mail router and
delivery program that works in the UUCP zone and on the Internet and
that is capable of gatewaying between the two.
SVR4 mail supports SMTP, UUCP mail, alias files, forwarding files,
mailing list directories, /etc/hosts files, the domain name system, and
can also query uucp for neighboring sites, automatically. (System V
Release 4.1 also allows batching of multiple messages into a single UUCP
transaction, and allows many addresses to be passed with a single
message transfer, which can greatly decrease the traffic generated for
large mailing lists.) It is also very simple to configure with a
reasonable certainty of correctness.
It also supports mail-to-pipe and mail-to-file.
SVR4 mail uses configuration files to resolve addresses based on their
syntax, somewhat similar to sendmail, but using regular expressions and
a more easily understood syntax. The set of methods that SVR4 mail uses
for resolving local and remote addresses and hosts is configurable and
extensible.
Questions related to SVR4 mail are usually discussed in comp.mail.misc.
SVR4 mail is a standard part of System V Release 4; unfortunately, some
vendors have not realized that SVR4 mail is not the same mailer as the
SVR3 mail system, and have replaced it with other inferior mail systems.
deliver: Author Chip Salzenberg* <chip@fin!chip@dg_rtp.dg.com>
Deliver allows any user to write a shell script that processes all
incoming mail messages for that user. The system administrator may
also install scripts that process all messages by installing
it as the Local Delivery Agent (lmail replacement).
The output of a script is a list of mail addresses, files and programs
that should receive the message. It has access to each message as it
is processed, so the action can be content dependent. The script may
also generate automatic replies, like the "vacation" program, or pass
along a modified version of the original message.
Deliver can be used to construct mail-based services (e.g. automatic
mailing list maintenance). It can also be used to filter mail
automatically in prearranged ways (e.g. encryption and decryption,
tossing junk mail, or vacation notices).
Deliver was last posted in comp.sources.reviewed, volume 1. The
current version is 2.1.12.
It can be retrieved from <ftp:ftp.cs.uni-sb.de/pub/mail/deliver>
procmail: Author Stephen R. van den Berg*
<be...@pool.informatik.rwth-aachen.de>
Can be used to create mail-servers, mailing lists, sort your incoming
mail into separate folders/files (real convenient when subscribing to
one or more mailing lists or for prioritising your mail), preprocess your
mail, start any programs upon mail arrival (e.g. to generate different
chimes on your workstation for different types of mail) or selectively
forward certain incoming mail automatically to someone.
Procmail can be used:
- and installed by an unprivileged user (for himself only).
- as a drop in replacement for the local delivery agent /bin/mail
(with biff/comsat support).
- as a general mailfilter for whole groups of messages (e.g. when
called from within sendmail.cf rules).
The accompanying formail program enables you to generate autoreplies,
split up digests/mailboxes into the original messages, do some very
simple header-munging/extraction, or force mail into mail-format (with
leading From line).
Also included is a comprehensive mailinglist/archive management system.
Since procmail is written entirely in C, it poses a very low impact
on your system's resources (under normal conditions, when you don't
start other programs/scripts from within it).
Procmail was designed to deliver the mail under the worst conditions
(file system full, out of swap space, process table full, file table
full, missing support files, unavailable executables; it all doesn't
matter). Should (in the unlikely event) procmail be unable to deliver
your mail somewhere, the mail will bounce back to the sender or reenter
the mailqueue (your choice).
A recent version can be picked up at various comp.sources.misc archives.
The latest version (3.03) can be obtained directly from the ftp-archive at:
ftp.informatik.rwth-aachen.de (137.226.225.3)
(g)zipped: pub/packages/procmail/procmail.tar.gz <160KB
compressed: pub/packages/procmail/procmail.tar.Z <224KB
[Ed note: I had noted reported difficulties in integrating procmail
with System V and/or smail 2.5. The 2.70 version of Procmail eliminated
these difficulties.]
mailagent: Author Raphael Manfredi* <r...@hptnos02.grenoble.hp.com>
The mailagent is yet another mail filter, written in perl, which
will let you do anything with your mail. It has all the features
you may expect from a filter: mailing lists sorting, forwarding to
MTA or to inews, pre-processing of message before saving into
folder, vacation mode, etc... It was initially written as an
ELM-filter replacement, but has now enough power to also supplant
MMDF's .maildelivery. There is also a support for @SH mail hooks,
which allows you to automatically distribute patches or software
via command mails.
The mailagent was designed to make mail filtering as easy as it can
be. It is highly configurable and fairly complete. Rules are
specified in a lex-like style, with the full power of perl's
regular expressions. The automaton supports the notion of mode, and
header selection has many magic features built-in, to ease the rule
writing process.
To give a simple example, the two following rules:
Subject: /cron output/ { SAVE cron };
To Cc: dist-users { FORWARD fri...@acri.fr; LEAVE };
would save in a folder 'cron' all cron-related mail, and forward
mail from the dist-users mailing list to a friend, leaving a copy
in the system mailbox for immediate processing...
It supports delivery to plain UNIX folder, to MMDF-style folders or
to MH folders with built-in unseen sequence updates, as specified
in your ~/.mh_profile. It may therefore replace MH's slocal program
as well.
Mailagent can be dynamically extended (that's the advantage of
having it written in perl) with new filtering commands that will
behave exactly like built-in ones; this operation being done
without changing a single source line in the program itself, of
course. It also provides a generic mail server layer, where
user-defined commands can be easily plugged in, mailagent taking
care of the lower-level stuff.
The distribution comes with a set of examples, an exhaustive test
suite, and naturally a detailed manual page. It should be noted
that the mailagent will work even if your system administrator
forbids "| programs" hooks in the ~/.forward, provided you have
access to some sort of cron daemon.
The mailagent program is available from any comp.source.misc
archive and thanks to Christophe Wolfhugel
<Christophe...@grasp.insa-lyon.fr>, from ftp.univ-lyon1.fr
(134.214.100.6) under /pub/unix/mail/tools, file
mailagent-3.0.tar.gz
pathalias: Author Peter Honeyman
[Not recommended anymore, due to the shift away from UUCP. Included
for historical interest, and the occasional use in very special
situations.]
Pathalias reads the UUCP Map Project maps (they need to be extracted
from the postings first) and constructs a database containing the
minimum cost route to any machine in the maps. This database can
then be used with any mailer that knows how to search the database
(eg: smail 2.5, Zmailer?, and some versions of sendmail. Smail 3
comes bundled with pathalias).
There were previous versions of this program. You must use
pathalias version 10 (latest version), because some map format
changes have been made and only pathalias 10 can parse them.
If your pathalias doesn't give a syntax error on:
echo "file {foo}" | pathalias
It's the new one.
There were other route-generating programs, but all (as far as
I know) are very obsolete, and none run as fast as pathalias
(still, which can be rather hard on machines with smallish virtual
memory or RAM capacities).
pathalias 10 is available from comp.sources.unix archives,
volume 22. A patch was just released in comp.sources.unix
(vol 25) that addresses an oddity when used with smail (not that
I've ever noticed it).
uuhosts: Author John Quarterman
[Not recommended anymore. Included for historical interest.]
The "defacto" standard UUCP Map Project map unpacker. Includes
a program to arbitrarily view individual map entries. Uuhosts
implements trojan horse/virus security by running under
a "chroot()" system call. Uuhosts does not appear to be
actively maintained, and the last versions that I have inspected
were unable to easily compress the maps (a full set of maps
is >6000 blocks), had no provision for automatically
running pathalias, and will not work with the newest version
of cnews. Further, uuhost's header checking is so picky
that the slightest change in the map format will cause
uuhosts to reject map updates.
Use of uuhosts now will require some minor hacking - and this
hacking will stretch your knowledge of Bourne shell programming.
The last edition, "uuhost4" (version 1.69) appears to have
been posted in comp.sources.unix in volume 3, 1986.
Do not be confused by Jan-Piet Mons "uuhost 2.0" program posted
in alt.sources. This is not a map unpacker. It is just
a map viewer, and is a subset of the real uuhosts.
unpackmaps: Author Chris Lewis* <cle...@ferret.ocunix.on.ca>
[Not recommended anymore, sniff ;-)]
Unpackmaps is a superset of the functionality of uuhosts.
It obtains its security by doing the map unpacking with
a specialized parser that knows the map article format
rather than invoking a shar/shell. Compression and pathalias
invocation is automatic, correctly takes into account
the change date of local configuration files, and will
work with the latest Cnews.
The newest version of unpackmaps, version 4.1, has been
released to comp.sources.misc, and appeared in volume 34.
This version is entirely written in C, is considerably faster
than unpackmaps 3 or uuhosts, has considerably more features,
and will work with Brian Reids PostScript net maps too.
unshar: Author Lee Ward, modified by Mark Moraes* <mor...@deshaw.com>
unshar is evolved from getmaps by Lee Ward. It is has a specialized
and limited parser that understands most simple shar formats. It is
capable of automatically unpacking new files from a newsgroup spool
directory, and requires no interaction whatsoever with the news
system. Apart from UUCP maps, it can be used to automatically and
safely unpack shar files from the sources newsgroups. It does not
handle some of the newer, esoteric shar formats that do automatic
uudecodes, etc. Ftp'able from
ftp.cs.toronto.edu:/pub/moraes/unshar.tar.gz.
Chris Lewis
Last-modified: Thu Nov 12 10:23:46 EST 1998
UNIX EMail Software - a Survey
Chris Lewis
cle...@ferret.ocunix.on.ca
[and a host of others - thanks]
Copyright 1991, 1992, 1993, Chris Lewis
Redistribution for profit, or in altered content/format
prohibited without permission of the author.
Redistribution via printed book or CDROM expressly
prohibited without consent of the author. Any other
redistribution must include this copyright notice and
attribution.
------------------------------
Subject: Configuration Issues:
What you need for email connectivity is determined by:
1 What networks you intend to connect to.
The Internet (hence SMTP)? UUCP sites? X.400?
Bitnet? Others? Combinations?
2 What links you have or are willing to install
Internet T1? T2? UUCP? Other? [Details on how to
make your connections is beyond the scope of this FAQ,
but can usually be found out from the provider (other end)
of the link]
3 what user interface you want to use. This is largely
an independent issue, so consult the Specific Package
Reviews directly.
------------------------------
Subject: Recommended MTA Configurations:
These configurations are based upon my own experience, and the
experience of others. Careful installation of any of these
configurations will result in a solid, reliable mail system
that respects the appropriate "do's and don'ts". Each configuration
represents a compromise of ease of installation and maintenance
versus sophistication and capabilities.
One thing you should consider is what you already have on your
system. You will invariably have "binmail", and will have a good
chance at already having sendmail. Some systems come with
smail (if 2.3, junk it) The configurations shown below are *minimal*
configurations, so you should consider whether you want to use what
you already have or not.
Scenario 1: Only UUCP connections.
Smail 2.5. If you want to set up a routing database of
your own, you will also need pathalias, and unpackmaps or
uuhosts. Instead, though, you can configure smail 2.5 to
smart-host most destinations to a nearby friendly site
who'll do your routing for you without having to run
the routing software. Note further, that you can run
pathalias on just a subset of the full set of maps.
[Unpackmaps makes this particularly easy to do]
Smail 2.5, as shipped, does not support mail-to-pipeline
or mail-to-file aliasing. If you need these, at a minimum,
you should obtain lmail. If you intend more than casual
use of these features, it is recommended that you obtain
deliver or procmail instead of lmail.
Even if you have sendmail already, you can integrate smail 2.5
with it to do your UUCP routing. (though, some later versions
of sendmail can do routing themselves)
If you're a little more demanding of your mail connections, smail 3
is also a good choice, and works particularly well for systems that
are UUCP connected to Internet sites.
Scenario 2: SMTP connections (optionally, some UUCP connections too).
Generally speaking, sendmail will do this for you and you have
a good chance to have it already. However, for the novice, it
is recommended that smail 3 be used instead [see review of
sendmail below]. Smail 3 includes all of the routing software
and can do mail-to-pipeline and mail-to-file, so none of the auxiliary
programs mentioned in scenario 1 are necessary.
Most sendmails don't include UUCP routing mechanisms, so you would
need pathalias and unpackmaps or uuhosts if you wish to set up
a UUCP routing database. Further, most sendmails don't know
how to query a pathalias database directly, so you may have to hack
your own path lookup program into the sendmail.cf (smail 2.5 can
be used for this purpose provided that you will have a UUCP link
to the outside world)
Both MMDF and PP can also be used, but PP is usually overkill.
Deliver or procmail are still quite useful in this configuration
for extended alias facilities.
Scenario 3: Connections to other networks (optionally including
SMTP or UUCP), or very high loading.
Your best bets are MMDF, PP or zmailer.
You can implement other network interfaces with sendmail, but
not only will you probably have to roll your own, but sendmail
can't cope with high loading very well. Ditto smail 3.
There are other configurations. See the Package Reviews to
determine which packages are appropriate.
------------------------------
Subject: Package Reviews
Honesty requires me to point out which software packages were
reviewed by their author (including me ;-). I do so by appending
a "*" to the name of the author. In some cases, the material
has been cribbed from FAQ's or general information blurbs.
It is worth noting, though, that most of these packages are well
known, and have been in operation at many sites for periods of
a year or more. These packages do their job well, and have been
extensively thrashed out in the best debugging laboratory in the
universe (Usenet ;-)
A few packages have been mentioned prior to their release.
(unpackmaps 4, the occasional beta version). It is
recommended that these versions be avoided by novices until they
have had a chance to settle for a little while. This FAQ will
note when such software seems (according to rumour *I* hear) to be
stable enough for general use.
Some of these packages are capable, by various bits of hackery,
of doing a lot more than is claimed for them. But I refrain
on telling you how to "take the covers off". Given the
intended audience, that would be tantamount to trying to
teach preschoolers do-it-yourself brain surgery. Please don't
take this as condescending - I've been working on/in/with email
systems for over 12 years and I *still* won't play with (as
just one example) sendmail.cf's.
Therefore, I restrict myself largely to "out-of-the-box" functionality,
"fill-in-the-blank" configurability, and normal documented installation
procedures. Beyond that, you're on your own.
binmail
binmail is usually really called "mail". On System V prior to
Release 4, it is a really simple UA that does dual duty as the
TA. It's pretty awful because it doesn't know how to set up
headers properly, doesn't even know what a "Subject:" line is,
and there's no way to do any kind of aliases.
On BSD, binmail invokes sendmail to do the MTA function. On
System V prior to Release 4, you really do want to replace binmail's
MTA functionality with something else. However, you should not
replace it in its "mail" (UA) functionality, because many
system-level administration mechanisms will break. Any new UA
should be installed as a different name than "mail".
Beginning with System V Release 4, "binmail"'s transfer agent
capabilities were considerably enhanced to have similar capabilities
to Smail 3 and sendmail. There is usually no need to replace it with
another mail agent. (See SVR4 mail discussion below)
Binmail stores mail in "mbox" format.
rmail
binmail's TA functionality is implemented by linking mail
to rmail. It's rmail that you'd want to replace with smail 2.5
etc.
The original BSD UA. It can support local profiles, aliases, folders,
header previewing, out-going mail recording and all sorts of good stuff.
An "okay" UA. Available from BSD "freed-sources" archives.
Mail stores mail in "mbox" format.
mailx
AT&T's answer to BSD "Mail", from which it is descended. Some versions,
such as the 3b1 one, should be avoided because of a buggy port. Not
available in source form (it's proprietary but ubiquitous enough to be
mentioned here).
Mailx stores mail in "mbox" format.
mush: author Dan Heller* <ar...@well.com>
The "Mail User's Shell" is a "shell" for mail users. That is, it
has its own environment where you can configure not only the user
interface, but the actual internal mechanisms. Internally, mush
has a csh-like scripting language, altho it's not as powerful as
csh. It has command-line aliases, file completion, if-else state-
ments, command piping, and so on. Because you can build your own
commands, you can virtually build your own library of email features.
Mush has two tty-based interfaces: the standard tty-mode (ala BSD
Mail or sys-v mailx) and the fullscreen/curses mode (ala vi, emacs
or even Elm). You can set up key bindings that execute one or more
mush commands, personalized commands or even UNIX commands. You
can even emulate keyboard input with keyboard macros and mappings.
Mush also has a SunView interface that is more powerful than Sun's
Mailtool, yet backwards compatible with most versions. Most sunview
users (if there are any left these days) prefer MushView over Mailtool.
The current version of Mush is 7.2.5. All three interfaces are
available in one runtime binary. Except for the MushView interface
(which is only available on for suns), Mush is portable to
everything that runs UNIX. There is also a DOS port available for
PCs and can run on most 286 machines. An older version of Mush
(6.5) can run on as little as 640 of RAM. (Mush-PC is typically
used with UUPC.)
The "next generation" of Mush is a commercial product called Z-Mail
from Z-Code Software (mail in...@z-code.com for details). All aspects
of Mush are retained, yet it has grown to be far more powerful. It
runs under X windows with either a Motif or Open Look interface
and also supports multi-media, user "functions" and a suite of new
features.
Mush stores its messages in "mbox" format, or MMDF format if you're
using MMDF as your MTA.
The newsgroup comp.mail.mush is dedicated to it.
[Note: Z-Mail is not related at all to Zmailer. Zmailer is a MTA]
elm: coordinator Bill Pemberton <fl...@virginia.edu>
(cribbed from comp.mail.elm FAQ)
Elm is designed to run with "sendmail" or "/bin/rmail"
(according to what's on your system) and is a full
replacement of programs like "/bin/mail" and "mailx". The
system is more than just a single program, however, and
includes programs like "frm" to list a 'table of contents'
of your mail, "printmail" to quickly paginate mail files (to
allow 'clean' printouts), and "autoreply", a systemwide
daemon that can autoanswer mail for people while they're on
vacation without having multiple copies spawned on the
system.
The most significant difference between Elm and most other
mail systems is that Elm is screen-oriented. Upon further
use, however, users will find that Elm is also quite a bit
easier to use, and quite a bit more "intelligent" about
sending mail and so on.
Current release is Elm 2.4 PL25. Information on access is
available from the server at DSI.COM:
send mail to archive...@DSI.COM
send elm index
[Ed: elm is particularly good for novices. The only drawback
that I've heard is that elm is a bit less user configurable than,
say, mush]
MM: Contact Joseph Brennan* <inf...@cunixf.cc.columbia.edu>
Columbia University in the City of New York
(cribbed from MM man page.)
mm is a powerful electronic mail system which allows you to send, read,
edit and manage messages quickly and easily. It is designed to have the
same interface as the MM program written and developed for DEC20s over a
period of many years.
mm was written using the CCMD package developed at Columbia. Thus, it
has copious internal help, completion of partially typed commands on use
of the TAB key, and help on partial commands when ? is typed.
mm can read several mail-file formats. Its default is mbox, the same
format used by unix mail. It also can read babyl, used by emacs rmail,
and mtxt and MH. It can copy messages from one file type to another.
MM is a Freeware MUA copyright by Columbia University (as is this
description).
MM is available by anonymous ftp from cunixf.cc.columbia.edu, directory mm.
The file mm-intro.txt there is a longer description of how it was developed.
[Ed: MM also appears to be a good UA for novices. From the examples
in the manual page, it handholds extensively and is not screen oriented.]
MH: Maintainer John Romine <Bug...@ics.uci.edu>
The big difference between MH and most other "mail user agents" is
that you can use MH from a UNIX shell prompt. In MH, each command
is a separate program, and the shell is used as an interpreter. So,
all the power of UNIX shells (pipes, redirection, history, aliases,
and so on) works with MH--you don't have to learn a new interface.
other mail agents have their own command interpreter for their
individual mail commands (although the mush mail agent simulates a
UNIX shell). Mail messages are stored in individual files.
The current version of MH is 6.8.3 and supports MIME. MH comes
standard with Ultrix 4.0 and later, and AIX 3.1 and later.
via anonymous ftp:
ftp.ics.uci.edu [128.195.1.1] pub/mh/mh-6.8.tar.Z 1.6MB
louie.udel.edu [128.175.1.3] portal/mh-6.8.tar.Z 1.6MB
comp.mail.mh discusses MH, and contains a FAQ article.
Jerry Peek wrote a book about MH called "MH & xmh: E-mail for Users &
Programmers", ISBN 1-56592-027-9, published by O'Reilly and Associates,
second edition, September 1992.
XMH: <extracted from the manual page>
The xmh program provides a graphical user interface to the
MH Message Handling System. To actually do things with your
mail, it makes calls to the MH package. Electronic mail
messages may be composed, sent, received, replied to, for-
warded, sorted, and stored in folders. xmh provides exten-
sive mechanism for customization of the user interface.
xmh is part of the standard X distribution from the X Consortium.
EXMH: Author Brent Welch* <Brent...@sun.com>
exmh is an X interface to the MH mail system. It is written in John
Ousterhout's Tcl/Tk language system and requires that you have both
Tcl/Tk and MH installed. If you have metamail installed, exmh
supports MIME.
As well as providing the usual layer on top of MH commands, exmh
has a number of other features:
MIME support! Displays richtext and enriched directly. Parses
multipart messages. Displays hot buttons that invoke external viewers
(metamail) for things not directly supported. Built-in editor allows
simple composition of text/enriched format.
Color feedback in the scan listing so you can easily identify
unseen messages (blue), the current message (red), deleted
messages (gray background), and moved messages (yellow background).
Xresources control these color choices.
A folder display with one label per folder. Color highlights
indicate the current folder (red), folders with unseen messages
in them (blue), and the target folder for moves (yellow background).
Nested folders are highlighted by a shadow box. A cache of
recently visted folder buttons is also maintained. Monochrome
highlights are reverse video for the current folder, bold box
for folders with unseen messages, and stippled box for the
target of move operations.
Clever scan caching. MH users know that scan is slow, so
exmh tries hard to cache the current state of the folder to
avoid scanning. Moves and deletes within exmh do not
invalidate the cache, and background incs that add new messages
are handled by merging them into the scan listing. The
scan cache is compatible with xmh.
Numerous other features, such as "facesaver" display, backgrounds,
dialog-box interface to MH "pick", folder searching and listing,
designed for inclusion of user "hooks" and interfaces etc.
<ftp://parcftp.xerox.com/pub/exmh/exmh-1.5.3.tar.Z>
<ftp://ftp.aud.alcatel.com/tcl/code/exmh-1.5.3.tar.gz>
<http://www.sunlabs.com/~bwelch/exmh>
GNU Emacs Rmail:
Rmail is an Emacs subsystem for reading and disposing of mail. Rmail
stores mail messages in Rmail files in BABYL format (originally used
under the ITS operating system), although it can incorporate new mail
from MMDF and Unix format files, or mixed-format files. Reading the
messages in an Rmail file is done in a special major mode, Rmail mode,
which redefines most letters to run commands for managing mail.
Rmail can do the standard things such as displaying, deleting, filing,
or replying to messages. Replying uses another Emacs subsystem, Mail
mode. Messages can be saved in either BABYL or Unix format. Rmail
maintains per-message attributes and user-defined labels. Rmail can
burst message digests.
VM: Author Kyle Jones* <ky...@uunet.uu.net>
VM (View Mail) is a GNU Emacs subsystem that allows UNIX mail to be read
and disposed of within Emacs. Commands exist to do the normal things
expected of a mail user agent, such as generating replies, saving
messages to folders, deleting messages and so on. There are other more
advanced commands that do tasks like bursting and creating digests,
message forwarding, and organizing message presentation according to
various criteria.
The current version of VM is VM 4.41.
FTPable from:
ftp.uu.net networking/mail/vm-5.72beta.tar.gz
archive.cis.ohio-state.edu pub/gnu/emacs/elisp-archive/packages/vm-4.41.tar.Z
VM is discussed in gnu.emacs.vm.info, or by mailing list by sending
an e-mail request to info-vm...@uunet.uu.net.
MH-E: Maintainer: Stephen Gildea <gil...@bbn.com>
MH-E is the GNU Emacs front end for MH. It offers all the
functionality of MH, the visual orientation and simplicity of use
of xmh, and full integration with Emacs, including thorough
configurability. The command set is similar to that of rmail (the
Emacs front end for BSD mail) and BSD mail itself. On-line help is
available.
Mh-e allows one to read and process mail very quickly: commands are
single characters and completion and defaults are available for
file and folder names. During a reply, the original message is
displayed simultaneously in another window for easy reference where
a mh-e command can quickly incorporate and format this text into
your reply.
With mh-e you compose outgoing messages in Emacs. This is a big
plus for Emacs users, but it has been known for non-Emacs users to
be able use mh-e after only learning the most basic cursor motion
commands. Mh-e is easily configured via the Emacs edit-options
menu, and people familiar with Emacs Lisp will be able to further
reconfigure mh-e beyond recognition.
The mh-e system is part of the standard GNU Emacs distribution.
The latest version can be found at
<ftp://ftp.x.org/misc/mh-e/mh-e-5.0.2.tar.Z>
[Above shamelessly stolen from Bill Wohler's comp.mail.mh faq]
C-Client: Author Mark Crispin <m...@panda.com>
C-client is a general library useful for creating MUA's. It provides
a high level logical interface for retrieving and manipulating
mail messages. It supports the latest draft of MIME (proposed
Internet standard for multipart, multimedia, typed electronic mail).
It is driver based, and easily ported to new platforms and MTA's,
already supports BSD, SysV, DOS, Macintosh and TOPS-20(!),
and supports present mail and mailbox formats.
Just the thing if you want to write a new MUA.
The package also contains a very fine IMAP and POP server.
<ftp://ftp.cac.washington.edu/mail/imap.tar.Z>
Metamail: Author N. Borenstein
[Described by Paul Eggert, egg...@bi.twinsun.com]
Metamail is a software implementation of Mime, designed for easy
integration with traditional mail-reading interfaces -- typically,
users do not invoke metamail directly. Ideally, extending the local
email or news system to handle a new media format is a simple matter
of adding a line to a mailcap file. Mailcap files are described in
RFC 1343: N Borenstein, ``A user agent configuration mechanism for
multimedia mail format information'' (June 1992). The source code
for metamail can be found in ftp.uu.net:mail/metamail/mm.tar.Z.
To join its mailing list, write info-metam...@thumper.bellcore.com.
MailManager: Author Mark Crispin <m...@panda.com>
A MUA implemented using C-Client for NeXT computers.
MMail: Martin R. Raskovsky* <mar...@atelier.demon.co.uk>
A WYSIWYG, text composition, visualization and MIME mailer. Text
organised in different fonts. Inline images. Shareware: Free, full
functionality 30 days evaluation. Academic Institutions: Free.
Pine: Authors Lundblade, Seibel, and Crispin <pi...@cac.washington.edu>
Pine is a mailer developed by the University of Washington Office of
Computing and Communications. It has been designed for ease-of-use and
with the novice computer user in mind. It is based on Internet mail
protocols (e.g. RFC-822, SMTP, IMAP, and MIME) and currently runs on
a variety of UNIX platforms, and a version is apparently available for
MSDOS.
The guiding principles for achieving ease-of-use in Pine were:
careful limitation of features, one-character mnemonic commands,
always-present command menus, immediate user feedback, and high
tolerance for user mistakes. It is intended that Pine can be learned
by exploration rather than reading manuals.
A stand-alone version of Pico, Pine's message composition editor, is also
included. It is a very simple and easy to use text editor with text
justification and a spelling checker.
Features:
- Mail index showing a message summary which includes the status,
sender, size, date and subject of messages.
- View and process mail with the following commands: forward, reply,
save, export, print, delete, capture address and search.
- Address book for saving long complex addresses and personal
distribution lists under a nickname.
- Multiple folders and folder management screen for filing messages.
- Message composer with easy-to-use editor and spelling checker.
The message composer also assists entering and formatting
addresses and provides direct access to the address book.
- Online help specific to each screen and context.
- Supports access to remote mail repositories via the IMAP2 protocol
defined in RFC-1176.
- Soon to support multi-part mail conforming to proposed MIME Internet
standard, allowing sending of sounds, graphics such as GIF and TIFF
files, and binary files such as spreadsheets.
Pine, including source code, is freely available via anonymous FTP from
ftp.cac.washington.edu on the Internet. Other provisions for distribution
have not been made. From the Internet, you may try out Pine and leave
comments by telneting to "demo.cac.washington.edu" and logging in as
"pinedemo". To join the Pine mailing list for announcements send a
email request to "majo...@cac.washington.edu" with body
"subscribe pine-info".
Pine is very portable and runs on a variety of UNIX machines including
DECstations, NeXTs, VAX's and Suns. Pine was originally based on Elm,
but it has evolved much since, ("Pine Is No-longer Elm").
For further information send e-mail to pi...@cac.washington.edu. Pine is
the work of Mike Siebel, Mark Crispin, and Laurence Lundblade at the
University of Washington.
Ream: Author: Paul Dourish* <dou...@europarc.xerox.com>
Ream is a curses-based mail user agent for a variety of UNIX flavours;
at one time or another, it's run on everything from a PC running Linux
to a Cray Y/MP running UNICOS. It was originally written at the
University of Edinburgh, and has spread not least through the
subsequent geographical distribution of alumni. It remains minimally
supported by its author (Paul Dourish <dou...@europarc.xerox.com>).
Ream is similar to elm in a number of ways, but considerably smaller
and with a stronger separation between MUA and MTA behaviours. It runs
over sendmail, mmdf and PP. It is available by anonymous ftp from
parcftp.xerox.com, in pub/europarc/reamXXX.tar.Z, where XXX is a
slowly incrementing version number.
ML: Author: Mike Macgirvin <Mike_Ma...@CAMIS.Stanford.EDU>
Current version 1.2.3. ML is a mail reader for the X window system,
using Motif and the IMAP protocol. It provides active filtering of
mail into user-defined views using a simple but powerful filter
language. For example:
"from john and since yesterday and undeleted"
defines a "view" of your mailbox containing only those messages. It
also has many features common to most modern mail systems,
including MIME attachments and USENET news support; the ability to
work with multiple open mailboxes, various sort options, spell
checking, address book, etc.
International support is more extensive than many mail programs;
although currently limited to 8-bit left-to-right languages.
International header and text encodings are invisibly handled so
users may work in their native language. Current work will extend
this support further.
ML is freely available via anonymous FTP to FTP-CAMIS.Stanford.EDU
in the directory "/pub/ml". Source code is available as well as
binary releases for several common system types. For more
information please see:
http://WWW-CAMIS.Stanford.EDU/projects/imap/ml
Z-Mail: Z-code Software Corp, Barbara Tallent* <tal...@ncd.com>
Z-Mail, a UNIX World Magazine "Product of the Year" winner for
1991, is a complete electronic mail system for workstations, PCs,
ASCII terminals and Macs. Z-Mail provides Motif and Open Look
graphical user interfaces, as well as two character modes. The
software has been ported to nearly every system that runs UNIX, and
it works with all standard UNIX mail transport agents including
sendmail, binmail, smail, MMDF and X.400 gateways. Z-Mail can
replace or coexist with standard mail user agents on the system,
including BSD Mail, AT&T mailx, Sun Mail Tool, Elm or Mush. Most
anyone can use Z-Mail "off the shelf" and immediately benefit from
its simple interface and advanced features.
The 'fullscreen' character mode has become its own product, Z-Mail Lite.
It's available immediately.
Z-Mail also includes Z-Script, a powerful scripting language that
enables users to customize and extend Z-Mail's capabilities. Z-Mail's
multi-media capabilities allow easy integration with best-of-class
products including spreadsheets, desk-top publishing, graphics, fax,
voice, and video. For example, when users receive a spreadsheet file,
Z-Mail can be configured to automatically launch the associated
application and load the the attachment automatically and transparently
to the user. Z-Mail understands MIME-format documents and is also
compatible with Sun's multimedia Mailtool.
For more information on Z-Mail, contact:
Z-Code Software Division
Network Computing Devices, Inc.
101 Rowland Way, Suite 300
Novato, CA 94945
tel: (415) 898-8649
fax: (415) 898-8299
E-mail: in...@z-code.com
URL: http://www.ncd.com/
You can obtain a demo copy of Z-Mail from ftp.z-code.ncd.com in the
directory pub/z-code/zmail/3.2 for assorted UNIX versions. The file
is named zm32.XXX.tar.Z where XXX is your type of machine. Windows
and Macintosh versions are also available for FTP in the directories
pub/z-code/zmail/zm-win and pub/z-code/zmail/zm-mac.
URLs:
ftp://ftp.z-code.ncd.com/pub/z-code/zmail/3.2/
ftp://ftp.z-code.ncd.com/pub/z-code/zmail/zm-mac/
ftp://ftp.z-code.ncd.com/pub/z-code/zmail/zm-win/win321/
Contact <ke...@z-code.com> for an activation key after downloading your
demo copy.
[As mentioned previously, Z-Mail is the commercial variant of mush. Ed]