Why are the "new/unread" status flags of mbox folders wrong in
folder view?

As written in manual.txt, the flags are determined by comparing
the timestamps of last access and modification. This can get
messed up if the folders are "touched" by other programs than
mutt, like "biff" or backup software.

There is also some issue with the "noatime" flag for mounting
filesystems (most often used on laptops). If "noatime" is
activated, no timestamp is updated for the last folder access,
i.e. Mutt cannot determine if the folder has received new mail
since last visited. You can recompile Mutt with the --buffy-size
option to "configure". Mutt will then use the folder size instead
of the access times. (This is only a workaround and might give
suboptimal results; another option is to use the MaildirFormat.) 

-- 
Jim Crumley                  |Twin Cities Linux Users Group Mailing List (TCLUG)
Ruthless Debian Zealot       |http://www.mn-linux.org/ 
Never laugh at live dragons  |