FreeBSD 5.3-R, postfix smtp dying with sig11

[Bryan Fullerton]

Below is an email I sent about this to the postfix-users list last
week, but there've been no replies so I'm forwarding it on to
freebsd-questions.

Thanks,
Bryan

---------- Forwarded message ----------
From: Bryan Fullerton <fehwalker at gmail.com>
Date: Wed, 5 Jan 2005 13:58:00 -0500
Subject: premature end-of-input on private/smtp socket
To: postfix-users at postfix.org


Howdy,

I've just moved my Mailman lists from an older machine (P3/933, U160
SCSI, no RAID, ECC RAM, FreeBSD 5.2.1) to a newer machine (P4/2.8G
w/HT, SATA on 3Ware 8006-2LP, RAID1, ECC RAM, FreeBSD 5.3).

I'm occasionally seeing messages from postfix in the maillog that
concern me. Specifically:

Jan  5 12:56:43 lists postfix/qmgr[30760]: warning: premature
end-of-input on private/smtp socket while reading input attribute name
Jan  5 12:56:43 lists postfix/qmgr[30760]: warning: private/smtp
socket: malformed response
Jan  5 12:56:43 lists postfix/qmgr[30760]: warning: transport smtp
failure -- see a previous warning/fatal/panic logfile record for the
problem description
Jan  5 12:56:43 lists postfix/master[30758]: warning: process
/usr/local/libexec/postfix/smtp pid 30911 killed by signal 11

So far today:
Jan  5 00:00:39 satori kernel: pid 98362 (smtp), uid 125: exited on signal 11
Jan  5 02:05:04 satori kernel: pid 2097 (smtp), uid 125: exited on signal 11
Jan  5 11:37:03 satori kernel: pid 20574 (smtp), uid 125: exited on signal 11
Jan  5 12:56:43 satori kernel: pid 30911 (smtp), uid 125: exited on signal 11

This isn't a mail loss issue, as the message will just be deferred and
delivered next time the queue is run. But it doesn't look good, and I
want to get to the bottom of the problem in case it's something
serious.

So... what could cause this? Is the sig 11 causing the failure, or is
master killing off smtp as a result of some other issue? Anything I
can poke at?

Thanks,
Bryan