4.2 sendmail trouble

[Alan Parker]

The following problem seems to just appeared out of the blue.  We run
4.2 on a 780 connected to the Internet and a local net.   About a week
ago we starting running out of file space on /usr.  After looking
around I found a >20 Meg incoming message (sun-spot digest) in
/usr/spool/mqueue.  The second line of the message was repeated
thousands of times; 20 Meg worth.   I deleted this file and rebooted
just to be sure of getting a clean state.  This weekend the problem
returned.  This time the huge message just starts with text, so I can't
tell where its coming from.

In addition, I also fine that after a while I have many (>12) 
"sendmail -bd -q1h" processes running.   This does great harm to the
load average.   How is this related to the other problem?   Any ideas
what my basic trouble is?

By the way, we've been running 4.2 since July and haven't seen this
problem before a week ago.  No sendmail hacking has been going on.

-Alan