Well, I had a very bad time with mailman and sendmail today. I was assuming
the problem was with sendmail. After screwing around with it all day, I'm
not so sure the problem is sendmail. I found the following items:
1) A LOT of people on the list have very slow mailservers. This is bad in
conjuction with the way mailman queues messages.
2) All the junk email coming into the list gets a "your post awaits
moderator approval" return email, and most of those domains don't exist, or
have servers that are extremely bogged down, also causing a problem with the
way mailman queues messages.
3) Mailman queues messages in very large groups. A single post to the list
generates 4 emails, each one with around 150 recipients. When sendmail
processes one of these single messages, as it sends to one of the recipients
and encounters a VERY slow mail server, everyone else on the recipient list
just sits and waits. The delays are... to me... well... horrid.
4) When I set mailman to send one email per recipient, sendmail still only
had one runner processing the queue. Of course, the same problem exists them
as #3.
Everything I tried seemed to make it the same or worse. I tried starting a
separate localhost only daemon of sendmail which doesn't do DNS lookups,
setting the outbound sendmail daemon for persistant queueing, put in a
caching only nameserver on the mailserver, set mailman to send one recipient
per message, etc. before running out of time to work on this. I suspect that
this all started with the upgraded mailman, this version apparently has it's
own message queueing and is very different from previous versions. I've
kinda hit the point of not being able to see the forest for the trees, so if
someone is up on mailman and sendmail I'd appreciate some insight. If you
have some thoughts (besides "dude, switch to using XXXXX for your MTA"),
please email me directly so I get the email quickly.
In response to the people who have suggested replacing sendmail... I would
like to call attention to what the website for mailman says. Bear in mind,
the mailman camp is somewhat anti-sendmail, instead favoring qmail, exim,
and postfix. However, note what THEY say about sendmail... "Moreover, with
appropriate work, sendmail can be configured to be the fastest and
highest-volume general-purpose MTA on the planet." This is in the section
where they compare sendmail to exim, qmail, and postfix. So I'm not the only
one who believes in sendmail.
I put things back the way they originally were. I'll ponder it over the
weekend.
Regards,
Jay West
jwest_at_classiccmp.org
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Received on Fri Oct 17 2003 - 16:38:20 BST