Here is a listing and description
of Tcl-based mail notification tools.  This is '''not'''
a comprehensive list.  Please don't add last night's hack.
Indeed, many people
have written biffs - it's so trivial to write a simple
one.  But few are truly professional, robust, flexible, etc.  
Here are several that appear to
be worthwhile.

   * tkbiff
     [http://expect.nist.gov/tkbiff]

     GUI: Shows message headers.  Click to show messages.
     User-definable action upon new mail: Message-dependent.
     OS: Windows, UNIX, MacOS
     Access: [IMAP], POP, APOP, SSL, UNIX mbox and maildir.

   * tclbiff
     (included with tkbiff - see above)

     UI: "You have mail from ..." on stdout.
     User-definable action upon new mail: Message-dependent.
     OS: UNIX
     Access: IMAP, POP, APOP, SSL, UNIX mbox and maildir.
     
   * xbiff2
     [http://www.linux-kheops.com/pub/xbiff2/xbiff2GB.html]

     GUI: Shows icon for no mail or new mail.
     User-defineable action upon new mail: Message-independent.
     OS: Windows, UNIX
     Access: IMAP, POP, UNIX mbox

   * mbiff
     [http://www.gnt.net/%7En5ial/Tcl]

     GUI: shows mailbox names containing new mail.
     User-definable action upon new mail: No.
     OS: UNIX
     Access: UNIX mbox
     Requires: TclX

   * tkgoodstuff
     [http://www-personal.umich.edu/%7Emarkcrim/tkgoodstuff/]

     GUI: Shows icon or count of messages in multiple mailboxes
          Click to show messages.
     User-definable action upon new mail: No.
     OS: UNIX
     Access: IMAP, UNIX mbox and MH.
     Status: Development ceased as of Oct '97.

   * tkpostage
     [ftp://ftp.procplace.com/pub/tcl/sorted/packages-7.6/x11/tkpostage-1.3b/tkpostage-1.3b.tar.gz]

     GUI: shows count of messages.  Click to show message headers.
     User-definable action upon new mail: No.
     OS: UNIX
     Access: UNIX mbox
     Status: appears orphaned, last release: 1.3b, Dec '95