I have a list named "supt" with 252 members that received an email that only went out to 1 recipient. After looking at the mailman smtp logs, I am seeing a number of lists that are only sending to a single recipient but have dozens to hundreds of members. Nothing is showing up in the "post" log for these problem lists. How do I troubleshoot this deeper? I still have many lists that seem to be working properly and actually have entries in the post log.
Postfix maillog
Oct 10 10:36:12 lists postfix/qmgr[11957]: B1E055055B7: from=<prvs=16239220b8=abc.xyz@theirdomain.com>, size=95926, nrcpt=1 (queue active) Oct 10 10:36:12 lists postfix/local[14994]: B1E055055B7: to=< supt@lists.mydomain.com>, relay=local, delay=0.13, delays=0.02/0/0/0.12, dsn=2.0.0, status=sent (delivered to command: /usr/lib/mailman/mail/mailman post supt)
Mailman smtp log
Oct 10 10:36:15 2012 (15296) < mailman.550.1349883373.15294.supt@lists.mydomain.com> smtp to supt for 1 recips, completed in 0.022 seconds
# list_members supt | wc -l 252