New Code!
After an interval of about 49 months, I went back into postoffice and fixed a long-standing defect in the way I handle mail filters where I passed the mail from: and rcpt to: headers down to milters with the trailing \r\n kept intact.
This had some unexpected problems with milters that took all the headers and attempted to reconstruct the mail message to send down to the part of the code that actually checked to see if it was spam. This had the annoying side effect, for me, of making a small subset of non-spam mail get flagged as spam. So tonight (2-Feb-2015) I went back into the guts of postoffice and fixed (I hope!) that wagon.
So, with the release of version 1.5.8 postoffice is tanned, rested, and ready. (To crash? To function properly? It Works For Me™ – maybe it will for you.)