*does his best Rom imitation* Dooooes... thismeanPublish8iscomingsoon?
Edit: If I do a mailsave containing mails I've already saved, I presume it either ignores those mails or overwrites them, but does not under any circumstance duplicate them? It did seem to be saving them by message ID, which would suggest that I have nothing to worry about, but...
Speaking of which, I don't know if you can control this, but it might be nice if the file name included the subject. I found out the hard way that when you've got 240 vendor/bank/maintenance messages and only about a dozen messages you might conceivably want to keep, you have absolutely no easy way of knowing what's what post-save.