Hello again,

On Friday 22 February 2008, Arno wrote:
> On Friday 22 February 2008, FM wrote:
> > some customer have problem sending email to us.
> >
> > When they tested using telnet :
> > [EMAIL PROTECTED] bfreebody]$ telnet  mail.LEXUM.UMontreal.CA. 25
> > Trying 132.204.136.52...
> > Connected to mail.LEXUM.UMontreal.CA..
> > Escape character is '^]'.mail.LEXUM.UMontreal.CA
> > 220 gw-mail.lexum.umontreal.ca ESMTP
> > helo mail139.messagelabs.com
> > 250 gw-mail.lexum.umontreal.ca Ok.
> > mail from:<[EMAIL PROTECTED]>
> > 417 DNS lookup failure: bell.ca.  Try again later.
> > ^]
> > telnet> quit
> >
> >
> > What is courier-mta doing when user had the mail from ? I supposed it is
> > a dns lookup but of which fqdn ?
>
> Hmm, afaik a MX-record must be a hostname, not an alias (CNAME)..
> $ host -t mx lexum.umontreal.ca
> lexum.umontreal.ca mail is handled by 10 mail.lexum.umontreal.ca.
> lexum.umontreal.ca mail is handled by 20 smtps1.umontreal.ca.
> lexum.umontreal.ca mail is handled by 20 smtps2.umontreal.ca.
> $ host mail.lexum.umontreal.ca
> mail.lexum.umontreal.ca is an alias for gw-mail.LEXUM.UMontreal.CA.
> gw-mail.LEXUM.UMontreal.CA has address 132.204.136.52
>
> Change mail.lexum.umontreal.ca to an A-Record in your DNS and you're good
> to go.
>
> Sorry, don't remember the RFC for this, but I'm pretty sure that this is
> your problem.

On further consideration, think that this is _one_ problem... But maybe not 
what's causing the trouble. I get the following (rather old courier 0.53.2):
$ telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 hadante.dyn.bmit.de ESMTP
helo mail
250 hadante.dyn.bmit.de Ok.
mail from: <[EMAIL PROTECTED]>
250 Ok.

I'm just guessing (I didn't look at the code), maybe it's related to the fact 
that you need a tcp-dns-query to look up a valid ip-address a mx record for 
bell.ca?

$ host -t mx bell.ca
bell.ca mail is handled by 10 cluster3.eu.messagelabs.com.
$ host cluster3.eu.messagelabs.com.
[snip a lot of hosts]
;; Truncated, retrying in TCP mode.
[snip some more hosts]

Using bind-tools-9.4.1_p1 (gentoo)

I didn't look at the courier-code, but maybe that's part of the problem?
(Sorry, If I'm barking up the wrong tree, Sam)

--
Regards,

Arno

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