LDA understanding

[Muhammad Yousuf Khan]

i was just trying to understand LDA my understanding with postfix is
that postfix is an MTA and procmail is an LDA to deliver email however
i am using postfix alone and it is working great. it work with both
system user and virtual users with no issue. it receive email and drop
it to virtual user directory or system user directory.
so my question if postfix delivering the message to all the users then
what is the need of procmail/LDA?

[Stan Hoeppner]

The inbuilt Postfix delivery agent is very basic. It simply writes the
message to the mailbox, either mbox or maildir format.

It does not have delivery rules, nor a filtering language, and cannot
sort messages into IMAP folders, etc. Procmail and Dovecot LDA can do
these things, as well as others.

--
Stan

[Jerry]

On Thu, 14 Mar 2013 14:44:26 +0500
Muhammad Yousuf Khan articulated:

> i was just trying to understand LDA my understanding with postfix is
> that postfix is an MTA and procmail is an LDA to deliver email however
> i am using postfix alone and it is working great. it work with both
> system user and virtual users with no issue. it receive email and drop
> it to virtual user directory or system user directory.
> so my question if postfix delivering the message to all the users then
> what is the need of procmail/LDA?

Personally, I have no idea why anyone uses "procmail". For relatively
fine grain sorting of mail upon delivery, I use Dovecot and Sieve. From
what I can ascertain, procmail hasn't even been maintained in over a
decade.

Just my 2¢ on the matter.

--
Jerry ✌
postfi...@seibercom.net
_____________________________________________________________________
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[Muhammad Yousuf Khan]

Thanks guys, i am using dovecot but i didn't knew in technical term we
call it LDA :P. but i thought procmail delivers emails to the
user-folder only, which i misunderstood , if dovecot, procmail and
courier are LDAs as i perceive from you emails. so no problem in
understanding the functionality of procmail as i am already using
dovecot.

Thanks,

[Andreas K.]

Στις , Jerry έγραψε:

> On Thu, 14 Mar 2013 14:44:26 +0500
> Muhammad Yousuf Khan articulated:
>
>> i was just trying to understand LDA my understanding with postfix is
>> that postfix is an MTA and procmail is an LDA to deliver email
>> however
>> i am using postfix alone and it is working great. it work with both
>> system user and virtual users with no issue. it receive email and
>> drop
>> it to virtual user directory or system user directory.
>> so my question if postfix delivering the message to all the users
>> then
>> what is the need of procmail/LDA?
>
> Personally, I have no idea why anyone uses "procmail". For relatively
> fine grain sorting of mail upon delivery, I use Dovecot and Sieve.
> From
> what I can ascertain, procmail hasn't even been maintained in over a
> decade.
>
> Just my 2¢ on the matter.

We have been using procmail on a relatively small set up (around 2000
users)
for about a decade. Rock solid has never refused to do anything I
wanted and I
can asuure you I have never used more than 5-10% of its abilities. I
have been looking
on Dovecot LDA recently just because of the Sieve language and its
integration
with many front ends (webmail apps etc).

Andreas

[Larry Stone]

On Thu, 14 Mar 2013, Jerry wrote:

> Personally, I have no idea why anyone uses "procmail". For relatively
> fine grain sorting of mail upon delivery, I use Dovecot and Sieve. From
> what I can ascertain, procmail hasn't even been maintained in over a
> decade.

I realize this gets away from Postfix per se but since LDAs are one of the
things Postfix has to work with, it's marginally on-topic.

I've used Procmail for years. That it hasn't been updated is irrelevant
because it just works. Software does not always have to be new to be the
right tool.

On the other hand, I've only recently delved into Dovecot and then only as
an IMAP/POP server. I had been using UW-IMAP, another software package
that has not been updated in years but one that unfortunately does not
"just work" for all cases (there is some issue between it and iOS Mail).
IMHO, Dovecot suffers from being too much and it wasn't until I understood
that there are three (maybe more?) distinct parts of Dovecot that operate
somewhat independently (IMAP/POP, LDA, and authentication) that I went
ahead implemented just the IMAP/POP piece dropping it in place of UW-IMAP
with no conversion or client reconfiguration (other than SquirrelMail)
required.

-- Larry Stone
lsto...@stonejongleux.com

[Kris Deugau]

Jerry wrote:
> Personally, I have no idea why anyone uses "procmail". For relatively
> fine grain sorting of mail upon delivery, I use Dovecot and Sieve. From
> what I can ascertain, procmail hasn't even been maintained in over a
> decade.

Sieve can't call outside programs (eg SpamAssassin) by design. IMO the
inability to call any external filtering programs (even from a
restricted whitelist) makes overall mail filtering significantly harder.

-kgd

[Reindl Harald]

usually sieve comes AFTER SpamAssassin because it is a broken
setup using a pre queue filter because it results in become
a backscatter and you are usually not permitted by law
accept a message with "250 OK" and drop it silent

[Ansgar Wiechers]

That would be a post-queue filter. A pre-queue filter rejects, so you
don't become a backscatter source.

Regards
Ansgar Wiechers
--
"Abstractions save us time working, but they don't save us time learning."
--Joel Spolsky

[Reindl Harald]

Am 14.03.2013 21:04, schrieb Ansgar Wiechers:
> On 2013-03-14 Reindl Harald wrote:
>> Am 14.03.2013 17:07, schrieb Kris Deugau:
>>> Jerry wrote:
>>>> Personally, I have no idea why anyone uses "procmail". For
>>>> relatively fine grain sorting of mail upon delivery, I use Dovecot
>>>> and Sieve. From what I can ascertain, procmail hasn't even been
>>>> maintained in over a decade.
>>>
>>> Sieve can't call outside programs (eg SpamAssassin) by design. IMO
>>> the inability to call any external filtering programs (even from a
>>> restricted whitelist) makes overall mail filtering significantly
>>> harder
>>
>> usually sieve comes AFTER SpamAssassin because it is a broken setup
>> using a pre queue filter because it results in become a backscatter
>> and you are usually not permitted by law accept a message with "250
>> OK" and drop it silent
>
> That would be a post-queue filter. A pre-queue filter rejects, so you
> don't become a backscatter source

sorry, yes, i reverted the terminology

however, in the order of Sieve it would be way too late to
call SpamAssassin because you CAN NOT reject at this time
and spam has to be REJETED long before LDA / Sieve

[Kris Deugau]

Reindl Harald wrote:
> Am 14.03.2013 17:07, schrieb Kris Deugau:
>> Sieve can't call outside programs (eg SpamAssassin) by design. IMO the
>> inability to call any external filtering programs (even from a
>> restricted whitelist) makes overall mail filtering significantly harder

By "harder" I mean that you end up going to a great deal of trouble to
properly deal with a message that user A really, really wants in their
Inbox, and which user B never ever EVER wants to see at all.

> usually sieve comes AFTER SpamAssassin because it is a broken
> setup using a pre queue filter because it results in become
> a backscatter and you are usually not permitted by law
> accept a message with "250 OK" and drop it silent

Laws vary by region. So far as my personal mail handling goes, I also
want to divert eg mailing lists like this one to a mail folder *before*
calling an expensive content filter on a message that isn't spam.

Wearing my ISP mail admin hat, we don't use procmail, but the mail flow
would be entirely compatible; there are several stages of filtering and
each one can short-circuit the process and deliver the message (either
to the Inbox or the Spam folder), instead of having to run *everything*
through an expensive SpamAssassin scan.

-kgd

[Reindl Harald]

Am 14.03.2013 21:31, schrieb Kris Deugau:

> Reindl Harald wrote:
>> usually sieve comes AFTER SpamAssassin because it is a broken

>> setup using a POST queue filter because it results in become

>> a backscatter and you are usually not permitted by law
>> accept a message with "250 OK" and drop it silent
>
> Laws vary by region. So far as my personal mail handling goes, I also
> want to divert eg mailing lists like this one to a mail folder *before*
> calling an expensive content filter on a message that isn't spam

forget the law

if you would be my mailadmin and kill messages with SpamAssassin
without reject them properly so a sane sender would get a bounce
from it's own mailserver i would kill you

[Tom Hendrikx]

On 03/14/2013 05:07 PM, Kris Deugau wrote:
> Jerry wrote:
>> Personally, I have no idea why anyone uses "procmail". For relatively
>> fine grain sorting of mail upon delivery, I use Dovecot and Sieve. From
>> what I can ascertain, procmail hasn't even been maintained in over a
>> decade.
>

> Sieve can't call outside programs (eg SpamAssassin) by design. IMO the
> inability to call any external filtering programs (even from a

> restricted whitelist) makes overall mail filtering significantly harder.
>
> -kgd
>

To complete this discussion, recent sieve standards/proposals have
support for a generic interface to external spam and virus filters such
as spamassassin, called at sieve runtime (i.e. not decisions based on
earlier added headers), see [1].

Pigeonhole sieve for Dovecot [2] supports this. pigoenhole also has
experimental support calling arbitrary external programs in an
administrator-controlled way [3], which I use with great success to add
spamtrap messages to a database.

I hope this might convince people to try sieve once more as a
replacement for procmail ;)

[1] http://tools.ietf.org/html/rfc5235
[2] http://pigeonhole.dovecot.org/
[3] http://wiki2.dovecot.org/Pigeonhole/Sieve/Plugins/Extprograms

--
Regards,
Tom

[James Griffin]

[--------- Thu 14.Mar'13 at 12:07:14 -0400 Kris Deugau :---------]

> Jerry wrote:
> > Personally, I have no idea why anyone uses "procmail". For relatively
> > fine grain sorting of mail upon delivery, I use Dovecot and Sieve. From
> > what I can ascertain, procmail hasn't even been maintained in over a
> > decade.
>
> Sieve can't call outside programs (eg SpamAssassin) by design. IMO the
> inability to call any external filtering programs (even from a
> restricted whitelist) makes overall mail filtering significantly harder.
>
> -kgd

Personally, I still use procmail and use it to pipe mail through
spamassassin, and also use it in conjuction with Dovecot LDA:

At the the top the procmailrc define the $DELIVER variable to
/usr/libexec/dovecot/deliver .

Then a simple rule:

:0
* ^List-Id:.*some.list.id
| $DELIVER -m mailbox

The -m switch automatically create non-existing Maildir++ mailboxes
should the not already be present. I Think it needs to be enabled in one
of the configuration files for Dovecot.

It works nicely, but then i'm sure the Dovecot sieve implementations
work well too; i've not tried them yet.


Cheers, Jamie.

--
James Griffin: jmz at kontrol.kode5.net
jmzgriffin at gmail.com

A4B9 E875 A18C 6E11 F46D B788 BEE6 1251 1D31 DC38

[Jerry]

On Fri, 15 Mar 2013 11:27:59 +0000
James Griffin articulated:

> [--------- Thu 14.Mar'13 at 12:07:14 -0400 Kris Deugau :---------]
>
> > Jerry wrote:
> > > Personally, I have no idea why anyone uses "procmail". For
> > > relatively fine grain sorting of mail upon delivery, I use
> > > Dovecot and Sieve. From what I can ascertain, procmail hasn't
> > > even been maintained in over a decade.
> >
> > Sieve can't call outside programs (eg SpamAssassin) by design. IMO
> > the inability to call any external filtering programs (even from a
> > restricted whitelist) makes overall mail filtering significantly
> > harder.
> >
> > -kgd
>
> Personally, I still use procmail and use it to pipe mail through
> spamassassin, and also use it in conjuction with Dovecot LDA:
>
> At the the top the procmailrc define the $DELIVER variable to
> /usr/libexec/dovecot/deliver .
>
> Then a simple rule:
>
> :0
> * ^List-Id:.*some.list.id
> | $DELIVER -m mailbox
>
> The -m switch automatically create non-existing Maildir++ mailboxes
> should the not already be present. I Think it needs to be enabled in
> one of the configuration files for Dovecot.
>
> It works nicely, but then i'm sure the Dovecot sieve implementations
> work well too; i've not tried them yet.

Sieve will happily create any non-existing mailboxes. Sieve is far more
robust than Procmail; however, you do have to do a bit of reading to
fully grasp what it can do.