[Mailman-Users] Sporadic, fractional non-delivery

Mark Sapiro msapiro at value.net
Thu Oct 5 19:47:02 CEST 2006

Jason LaMar wrote:

>We have an on-campus list with about 1,900 student subscribers that has been
>functioning properly for months. Recently, however, an extremely small
>percentage of students -- about 1% that we're aware of -- have stopped
>getting messages from the list.

The same students for each message?

>5. The impacted account names have been confirmed to reside in the Mailman
>config.pck file and via the Web GUI Membership Management screen with
>typical (non-digest) delivery preferences set.
>I should note that some of these students are automatically forwarding their
>University e-mail to an off-campus account -- like Gmail or Hotmail -- and
>obviously that introduces another layer of message filtering. But many of
>these students are using on-campus IMAP or POP e-mail resources only, and a
>spot check immediately after a message is distributed via Mailman reveals
>that they still aren't getting anything from the list.

How is this 'spot check' being done?

>Any ideas to help our investigation on the Mailman and/or Sendmail side? Is
>there some extra verbose logging that could be turned on?

It's pretty unlikely that this is a Mailman issue, but you can check
this by looking at Mailman's 'smtp' log. It will have an entry like

Oct 05 10:33:45 2006 (1570) <message-id> smtp for 170 recips, completed
in 4.645 seconds

The message should be delivered to nnn recips (170 in the above
example) where nnn is the number of message mode members with delivery
enabled less the poster if the poster doesn't receive her own posts
and less the number of members explicitly mentioned in To: or Cc: that
have the 'avoid dups' option.

If this number is as expected, then SMTPDirect delivered the message to
the MTA for all the expected recipients. You can also check Mailman's
'smtp-failure' log to see if any problems were reported to Mailman
during SMTP.

If the number of recips is short the number of missing deliveries, it
is a Mailman issue and we need to figure why Mailman is dropping
these, but I suspect from your analysis so far, that this isn't it.

If Mailman delivered to the expected number, then check the MTA's logs
because the problem is almost certainly in the MTA or outbound from

Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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