Here are some instructions for opening a mail folder that's in the
default folder directory for some mailers and newsreaders.

         Default Folder  
 Reader   Directory      Command line command  From within reader
 ======  ==============  ====================  ==================
 elm     ~/Mail          elm -f =folder        c =folder
 pine    ~/mail          pine -if folder       G folder
 mail    ~/mail          mail -f /path/folder
 nn      ~/News          nn +folder            G +folder
 
(Please send me information for other mailers and newsreaders.)

Pine has an incoming-folder variable which you can use to list your
incoming folders in a separate section of your folder list (to view
your folder list in Pine, type `L').  Setting this variable also
allows you to use the Tab key to step through all new messages in all
your incoming folders.  For more information see the question "How
can I filter messages into different incoming folders?" in the Pine
FAQ:

  http://www.cac.washington.edu/pine/QandA/FAQs.html#xtocid178164


IMPORTANT NOTE 
============== 
If you are going to be editing your incoming mail folder, e.g.,
deleting messages, then your filtering program and your folder reader
should use locking schemes that work together.  Otherwise, if mail is
delivered at the same time that you are deleting a message your
folder may be corrupted.  To learn more about locking see the
question "What is folder locking and how does it work?" in the Pine
FAQ.  This is useful to read even if you don't use Pine as your
mailer.

 http://www.cac.washington.edu/pine/QandA/sysadmins.html#xtocid7145

Most mailers, such as pine and elm, use lock a file named
`folder.lock' to lock the folder named `folder'.  Note that nn does
not lock folders so you probably don't want to use nn to delete
messages in a folder that is receiving incoming messages.  (Please
send me info about locking in other mailers and newsreaders.)

For more information about specific mailers and newsreaders, see the
relevant documentation, such as man pages and Web pages.  Some
pointers to documentation are listed in section 5.0.