[Mailman-Users] Mailman cannot deliver email to a particular domain

Adam McGreggor adam-mailman at amyl.org.uk
Wed Nov 20 00:28:04 CET 2013

On Tue, Nov 19, 2013 at 02:52:33PM -0800, Mark Sapiro wrote:
> On 11/19/2013 02:24 PM, Hung Phan wrote:
> > ... it seems that Mailman thinks canby.k12... domain is hosted at 10.30.xxx.xx, which is our internal DNS service. Is there a tool for us to trace the email sending route? 

You could look at your routing table(s), perhaps? (but see below).

>We suspect it is the DNS setting but need more info to determine where does it stop. Do we need an MX record, A record or something else in our DNS service so Mailman not try to connect to this DNS server and end up failing?

You could write a custom route in Exim, or a custom router/transport:
sometimes it's 'necessary' to define a route for a receiving MX,
particularly if the receiving MX is run by a clueless numpty (or,
indeed, someone who has a different interpretation of RFCs/Best
Practice etc than you).

> This has nothing to do with Mailman. It is strictly exim. Mailman is not
> doing any DNS lookups on anything except maybe localhost or whatever is
> set as SMTPHOST in Defaults.py/mm_cfg.py.
> Mailman passes the message and list of recipient addresses to this SMTP
> server (exim) and it's up to that server to deliver the mail.
> You have MX records
> $ dig mx canby.k12.or.us
> ...
> canby.k12.or.us.	86400	IN	MX	60 ALT2.ASPMX.L.GOOGLE.com.
> canby.k12.or.us.	86400	IN	MX	70 ASPMX2.GOOGLEMAIL.com.
> canby.k12.or.us.	86400	IN	MX	70 ASPMX3.GOOGLEMAIL.com.
> canby.k12.or.us.	86400	IN	MX	10 canby.k12.or.us.s9a1.psmtp.com.
> canby.k12.or.us.	86400	IN	MX	20 canby.k12.or.us.s9a2.psmtp.com.
> canby.k12.or.us.	86400	IN	MX	30 canby.k12.or.us.s9b1.psmtp.com.
> canby.k12.or.us.	86400	IN	MX	40 canby.k12.or.us.s9b2.psmtp.com.
> canby.k12.or.us.	86400	IN	MX	50 ASPMX.L.GOOGLE.com.
> canby.k12.or.us.	86400	IN	MX	60 ALT1.ASPMX.L.GOOGLE.com.

Internally, though, you may get a different result -- it could be worth
checking resolv.conf(5), nsswitch.conf(5), and `host -t ns` (or equivalent
through dig(1)).

> You would probably have better luck taking this exim issue to an exim
> support resource.

As a general purpose mail tool, swaks
<http://www.jetmore.org/john/code/swaks/> can often be quite useful.

"Should not the Society of Indexers be known as Indexers, Society of, The?"
    -- Keith Waterhouse

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