Why is the "To:" address changed?
Walt
I use my ISP's outgoing mail server to send email via sendmail.
I'm trying to send email to this address: fr...@diplomacy.born2play.org
I never received the expected automated reply, so I cc-ed myself and
found that something changed the To: address to fr...@born2play.org.
In other words, "diplomacy." was deleted in the To: address.
I tried sending to an intentionally bogus address
fr...@foobar.born2play.org, and the mail didn't get sent there, but at
least it was sent to "foobar.born2play.org".
nslookup diplomacy.born2play.org says
diplomacy.born2play.org canonical name = born2play.org.
so I'm guessing that this has something to do with
DNS and canonical names, something is converting
diplomacy.born2play.org to the canonical name born2play.org.
What is changing the outgoing email address? If it's sendmail,
is there anything I can do to change the behaviour?
I'm completely out of my comfort zone on this one....
Walt
Grant Taylor
> I'm using sendmail version 8.14.1 in Slackware 12.0. I use my ISP's
> outgoing mail server to send email via sendmail.
Ok...
> I'm trying to send email to this address:
> fr...@diplomacy.born2play.org I never received the expected automated
> reply, so I cc-ed myself and found that something changed the To:
> address to fr...@born2play.org. In other words, "diplomacy." was
> deleted in the To: address. I tried sending to an intentionally
> bogus address fr...@foobar.born2play.org, and the mail didn't get
> sent there, but at least it was sent to "foobar.born2play.org".
Check your Sendmail logs and see what addresses Sendmail showed the
message to be from and to. If Sendmail had the correct address,
something down stream made the change. If Sendmail showed the incorrect
address, there is something afoot that needs to be b-smacked.
> nslookup diplomacy.born2play.org says
> diplomacy.born2play.org canonical name = born2play.org.
Fine.
> so I'm guessing that this has something to do with DNS and canonical
> names, something is converting diplomacy.born2play.org to the
> canonical name born2play.org.
I doubt it.
I just telneted to port 25 on mail exchanger = 10 91-121-35-36.ovh.net
and spoke SMTP with their server. It appears as if the
fr...@diplomacy.born2play.org is a valid email address.
~> telnet 91.121.35.36.ovh.net 25
telnet: 91.121.35.36.ovh.net: Name or service not known
91.121.35.36.ovh.net: Unknown host
-3-S:2-gtaylor@rti02:~> telnet 91.121.35.36 25
Trying 91.121.35.36...
Connected to 91.121.35.36.
Escape character is '^]'.
220 ns28357.ovh.net ESMTP
ehlo rti02.co-lo.riverviewtech.net
250-ns28357.ovh.net
250-PIPELINING
250-STARTTLS
250-8BITMIME
250 SIZE 0
mail from:<gta...@riverviewtech.net>
250 ok
rcpt to:<fr...@diplomacy.born2play.org>
250 ok
rset
250 flushed
quit
221 ns28357.ovh.net
Connection closed by foreign host.
We know that what Sendmail (by default) will be doing is fine. So
unless you have made changes, chances are good that someone else is
monkeying around with things.
Do you have a Delivery Status Notification message that has some other
details in it? Or do you just have no response at all?
Check the path of the message that you CCed to your self? Is there any
thing strange about its headers?
Can we see the headers?
What log entries does your server have for the message ID for the CC
that you got?
> What is changing the outgoing email address? If it's sendmail, is
> there anything I can do to change the behaviour?
Unless you have set any thing up to cause Sendmail to change addresses,
I *HIGHLY* doubt that it is Sendmail that is doing it.
> I'm completely out of my comfort zone on this one....
*nod*
Give us some more information to work with and we will see what we can do.
Grant. . . .
Peter Peters
>> nslookup diplomacy.born2play.org says
>> diplomacy.born2play.org canonical name = born2play.org.
>
> Fine.
>
>> so I'm guessing that this has something to do with DNS and canonical
>> names, something is converting diplomacy.born2play.org to the
>> canonical name born2play.org.
>
> I doubt it.
But it does.
mail> host diplomacy.born2play.org
diplomacy.born2play.org is an alias for born2play.org.
born2play.org has address 91.121.35.36
The domain part of an e-mail address must either point to an MX or an A
records in the nameserver. You can't use CNAME's in an MX. Sendmail
knows this, so when he encounters a CNAME he changes it to the canonical
name to prevent issues with MX lookups. For more information about
sendmail and DNS check chapter 21 of the bat-book.
I think the administrator of born2play.org has not configured his system
to accept mail for @born2play.org addresses.
Peter Peters
Bill Cole
Walt <k9ge...@gmail.com> wrote:
For your .mc file:
define(`confDONT_EXPAND_CNAMES'.`True')
However, the real problem here is in DNS. RFC821 and RFC1123 both are
explicit: the domain part of an email address must be a domain with a MX
or A record, NOT an alias name that has a CNAME record. RFC1123's
construction of that mandate (section 5.2.2) even implies that a SMTP
sender should "canonicalize" domains before passing a message along, as
Sendmail does. Unfortunately, RFC2821 removed that prohibition,
resulting in a mess.
The logic behind the original ban, Sendmail's behavior, and similar
behavior over the years by other MTA's is based in a semantic nuance of
what a CNAME record really means, at least historically. A name that has
a CNAME record should be seen as a less proper name than the name the
CNAME resolves to, NOT as an alternative and independent identity. This
is why the DNS specification prohibits a name that has a CNAME record
from having other records (except for special DNSSEC types.) In recent
years, people who have missed that nuance have taken to using the CNAME
as a way to define secondary identities rather than inferior names, and
that conceptual mistake has bled back into operational practice and
expectations about DNS consumers giving more respect to the CNAME's
label than the DNS specification supports.
--
Now where did I hide that website...
D. Stussy
news:5c4e2$47c685fa$82592404$24...@news2.tudelft.nl...
> Grant Taylor wrote on 28-2-2008 2:18:
>
> >> nslookup diplomacy.born2play.org says
> >> diplomacy.born2play.org canonical name = born2play.org.
> >
> > Fine.
> >
> >> so I'm guessing that this has something to do with DNS and canonical
> >> names, something is converting diplomacy.born2play.org to the
> >> canonical name born2play.org.
> >
> > I doubt it.
>
> But it does.
>
> mail> host diplomacy.born2play.org
> diplomacy.born2play.org is an alias for born2play.org.
> born2play.org has address 91.121.35.36
>
> The domain part of an e-mail address must either point to an MX or an A
> records in the nameserver. You can't use CNAME's in an MX. Sendmail
> knows this, so when he encounters a CNAME he changes it to the canonical
> name to prevent issues with MX lookups. For more information about
> sendmail and DNS check chapter 21 of the bat-book.
That's not the situation.
One cannot use an alias name on the RIGHT-hand side (data) of an MX-RR. One
is permitted to get to an MX record by following a CNAME owned by the
original label (i.e. LEFT-hand side). What the OP has is an alias that
appears on the LHS of a CNAME record, not a label that has an MX record with
an alias on its RHS.
It appears that sendmail does canonicalize the domain part of a mailbox, but
it is NOT for the reasons you stated.