WMMail.app is a "mail-checker" like xbiff.  It indicates the status
of the user's mailbox by showing animated XPM icons when incoming
mails are detected.  Additionally, it can be configured to execute
a program on incoming mail and/or on mouse double-clicks, and can
provide a count of emails in the user's mailbox.  It currently
supports UNIX mbox files, MH and MailDir mail folders, and IMAP4
remote mailboxes.