I get this message 40 to 50 times per day on a low volume server.
(maybe 1000/day volume)
The corresponding reference in my mail log that is used by imap pop
and spamd shows the following:
Dec 8 07:18:50 dnsbureau spamd[281]: spamd: bad protocol: header
error: (Content-Length mismatch: Expected 9274 bytes, got 8123 bytes)
at /usr/bin/spamd line 1674, <GEN16> line 161.\n
The particular email did not have an attachment, so that could not be
a real issue. I'm using Unix sockets as it seems more stable to me
than an IP. Also, it does happen also sometimes, when no other
processes are running.
This problem started with 4.52, and on to 4.54 and 4.60 but it wasn't
present with 4.51.
I'm just trying to figure out if this is an Exim of spamd issue. If
you have some info, I'll appreciate it.