From: "Ted Mittelstaedt" <t...@ipinc.net>
At this point I am up against a wall. For starters this is an old ver of sa, old sendmail, etc. This server is scheduled for re-gen soon and there's no point in filing a bug on the old code. I will continue to observe and once the server is re-gened then if it keeps happening then I'll look into it further. I'll probably have to run the server for a few hours with SA turned off to get the raw spam, not something that is going to be very popular.
An old (really old) version of SA might show that problem. I seem to remember it being noted and fixed a long time ago. (2.3xish is when I started fiddling with this beastie.) You may be seriously stuck if you cannot upgrade. You might have to generate a special filter for your milter that looks for an empty second subject line and simply deletes it. {^_^}