[CentOS] OT: Strange Email Problem

Fri May 21 19:34:13 UTC 2010
Simon Billis <simon at houxou.com>

Simon Billis sent a missive on 2010-05-21:

Just to correct something I wrote:


> Susan Day sent a missive on 2010-05-21:
> 
>> Here are what the logs have to say:
>> 
>> @400000004bf6cfc4383bc65c delivery 6217: deferral:
>> CNAME_lookup_failed_temporarily._(#4.4.3)/ @400000004bf6cfc4383c5eb4
>> status: local 0/10 remote 0/255 @400000004bf6d51e34d61d8c starting
>> delivery 6218: msg 97881531 to remote suzieprogrammer at gmail.com
>> @400000004bf6d51e34d6449c status: local 0/10 remote 1/255
>> @400000004bf6d51e37303e14 starting delivery 6219: msg 97881555 to
>> remote suzieprogrammer at gmail.com @400000004bf6d51e373078ac status:
>> local 0/10 remote 2/255 @400000004bf6d51e373143cc delivery 6218:
>> deferral: CNAME_lookup_failed_temporarily._(#4.4.3)/
>> @400000004bf6d51e373241b4 status: local 0/10 remote 1/255
>> @400000004bf6d51e37807d0c delivery 6219: deferral:
>> CNAME_lookup_failed_temporarily._(#4.4.3)/ @400000004bf6d51e3780bf74
>> status: local 0/10 remote 0/255
>> 
> 
> Extract from: http://nixforums.org/about25455-Help-Diagnosing-
> CNAME_lookup_failed_temporar ily.html
> 
> "The likely cause of this is qmail's inability to handle large DNS
> packets. The most-recommended solution is to install dnscache (from
> djbdns), which trims off some unnecessary data and usually makes these
> packets small enough for qmail to handle. The more correct solution is
> to apply the "oversize DNS packets" patch to qmail (see qmail.org). A
> hackish-but-fast solution is to choose one of Earthlink's MXs, and put
> it in your smtproutes file. Not good long-term, but it will get the
> mail out of your queue while you work on a better solution."
> 
> I wouldn't put earthlinks mx in your smtproutes but you could put in
> you isp's if you wanted to as a quick and dirty fix.

It's been a long day, I'd not do the smtproutes but instead patch qmail or
install the djb dnscache - the issue is caused by large udp (I think)
packets being returned by the dns to qmail. I think that you could also use
a smart smtp host instead of sending the mail out directly (if you have
access to an smtp host that is working).

HTH

Simon.