MH Spool
........

   `nnmh' is just like `nnml', except that is doesn't generate NOV
databases and it doesn't keep an active file.  This makes `nnmh' a
*much* slower backend than `nnml', but it also makes it easier to write
procmail scripts for.

   Virtual server settings:

`nnmh-directory'
     All `nnmh' directories will be located under this directory.

`nnmh-get-new-mail'
     If non-`nil', `nnmh' will read incoming mail.

`nnmh-be-safe'
     If non-`nil', `nnmh' will go to ridiculous lengths to make sure
     that the articles in the folder are actually what Gnus thinks they
     are.  It will check date stamps and stat everything in sight, so
     setting this to `t' will mean a serious slow-down.  If you never
     use anything but Gnus to read the `nnmh' articles, you do not have
     to set this variable to `t'.