Unanswered mail hack

I'm having a hard time keeping track of mail I've already answered. To better keep track of my mail, I think I will split off my personal mail into several groups:

- mail.misc - mail.misc.archive for mail I've already answered and for my replies; threads I consider complete - mail.misc.noanswer for mail I want to archive but don't need to answer - mail.misc.all, a virtual group that lets me see and search through all the mail

All personal mail will be dumped into mail.misc.