One thing that I've always missed since I switched from pine to mutt was pine's more verbose e-mail notification. Instead of just saying "New mail in this mailbox." it would say something like:
[New mail from Philip Mak re New mail notification ideas] Also, pine checks for new mail when it is in the pager. In mutt's case, it doesn't, so if I stay inside the pager for hours then I won't see any new messages. I would like to suggest that these features (verbose new e-mail notification line, and check for new mail while in the pager) be implemented in mutt.