- need to add ``unalternates''

- Other than multipart/mixed and PGP/MIME, Mutt should allow the user to
  specify what to do with other types of multipart messages (i.e., so a user
  can deal with S/MIME messages reasonably)

- option to not include attachments in replies

- handle message/external-body in some fashion

- automatic POP mail checking

- read/write the .mh_sequences file?

- not possible to view the header of a single part message which contains
  something that requires a mailcap entry to view

- need to clean up the error recovery when running out of space when syncing
  a mbox/mmdf mailbox

- allow replying to message/rfc822 attachments

