Mail and Procmail
-----------------

   Many people use `procmail' (or some other mail filter program or
external delivery agent--`slocal', `elm', etc) to split incoming mail
into groups.  If you do that, you should set `nnmail-spool-file' to
`procmail' to ensure that the mail backends never ever try to fetch
mail by themselves.

   This also means that you probably don't want to set
`nnmail-split-methods' either, which has some, perhaps, unexpected side
effects.

   When a mail backend is queried for what groups it carries, it replies
with the contents of that variable, along with any groups it has figured
out that it carries by other means.  None of the backends (except
`nnmh') actually go out to the disk and check what groups actually
exist.  (It's not trivial to distinguish between what the user thinks is
a basis for a newsgroup and what is just a plain old file or directory.)

   This means that you have to tell Gnus (and the backends) what groups
exist by hand.

   Let's take the `nnmh' backend as an example.

   The folders are located in `nnmh-directory', say, `~/Mail/'.  There
are three folders, `foo', `bar' and `mail.baz'.

   Go to the group buffer and type `G m'.  When prompted, answer `foo'
for the name and `nnmh' for the method.  Repeat twice for the two other
groups, `bar' and `mail.baz'.  Be sure to include all your mail groups.

   That's it.  You are now set to read your mail.  An active file for
this method will be created automatically.

   If you use `nnfolder' or any other backend that store more than a
single article in each file, you should never have procmail add mails to
the file that Gnus sees.  Instead, procmail should put all incoming mail
in `nnmail-procmail-directory'.  To arrive at the file name to put the
incoming mail in, append `nnmail-procmail-suffix' to the group name.
The mail backends will read the mail from these files.

   When Gnus reads a file called `mail.misc.spool', this mail will be
put in the `mail.misc', as one would expect.  However, if you want Gnus
to split the mail the normal way, you could set
`nnmail-resplit-incoming' to `t'.

   If you use `procmail' to split things directory into an `nnmh'
directory (which you shouldn't do), you should set
`nnmail-keep-last-article' to non-`nil' to prevent Gnus from ever
expiring the final article in a mail newsgroup.  This is quite, quite
important.