Why does Mail screw up the subject lines?



I'm forwarding mail from work to home (OS X Tiger at home). When the messages arrive, the subject lines don't match the messages. Almost always they are in reverse order of when they were received. (That is, if there are messages 1, 2 and 3 with headers a, b, and c, I get a-3, b-2, c-1.) Messages from my home ISP are fine however.

Any idea what's going on here?


P.S. Rebuilding the mailbox solves the problem but this is a pain to do every time I want to read my mail! :(