Sendmail problems: Unexpected close on connection

[lug-TwWeWiF2EGRi+ztankeudA at public.gmane.org (Don Levey)]

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I've been running Sendmail on my home server for the better part of 8
years, and for the most part it's been going swimmingly.  However, it's
just been brought to my attention that I've been receiving increasing
numbers of the following error:

Jan 12 15:53:59 dungeon sendmail[3951]: n0CKldh7003951: collect:
premature EOM: unexpected close
Jan 12 15:53:59 dungeon sendmail[3951]: n0CKldh7003951: collect:
unexpected close on connection from example.com,
sender=<address-hcDgGtZH8xNBDgjK7y7TUQ at public.gmane.org>
Jan 12 15:53:59 dungeon sendmail[3951]: n0CKldh7003951:
from=<address-hcDgGtZH8xNBDgjK7y7TUQ at public.gmane.org>, size=0, class=0, nrcpts=1, proto=ESMTP,
daemon=MTA1, relay=mirror.example.com [ip address]

By "increasing" I mean that I've seen over 2000 so far in the past 2
days, 1800 in the two weeks before that, and 3 in the two weeks before that.

I tried the solution suggested here:
http://lists.mailscanner.info/pipermail/mailscanner/2007-September/078143.html

and while it looks like it might have slowed things down somewhat it's
not eliminating the errors.  I had recently implemented a new DNSBL in
my sendmail config, but backing that out seems to have had no effect.  I
can't identify any other change that could account for this.

Considering the problem, I may not see your response :-) but if anyone
has suggestions please let me know.

Thanks in advance,
 -Don Levey
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