When Mutt Thinks Mailboxes Always Have New Mail

On SDF the non-inbox user mail files are accessed via an NFS mount.
Mutt [0]has a hard time figuring out when an NFS mbox file has been
modified in some circumstances. So when you press 'c' in the index
view, your mailboxes always appear to have new mail. Highly
irritating. The fix is to add "set check_mbox_size=yes" to your
.muttrc (apparently this works only in more recent versions of mutt,
the one on SDF is 1.5.19. Older versions [pre 1.5.15] can use a
compile- time option "+BUFFY_SIZE").

[0] http://mutt.org