cleaner and less invasive, and I'm not so worried about memory leaks
  now.

* Fixes the bug where mutt would append a '/' to $folder even if it
  was only {mailhost}, causing mutt to browse the root directory
  instead of the home directory.

* includes a first stab at preserving the D flag on the IMAP server.
  Now if you answer no to 'Purge deleted', the server still stores
  the messages as deleted, but doesn't expunge them on exit.

  NOTE: this is a first attempt. Play around, but don't mark things
  as deleted that you'd be sorry to see disappear.

(From: Brendan Cully <brendan@kublai.com>)