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Choosing a Mail Backend
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   Gnus will read the mail spool when you activate a mail group.  The
mail file is first copied to your home directory.  What happens after
that depends on what format you want to store your mail in.

Menu

Unix Mail Box
Using the (quite) standard Un*x mbox.
Rmail Babyl
Emacs programs use the rmail babyl format.
Mail Spool
Store your mail in a private spool?
MH Spool
An mhspool-like backend.
Mail Folders
Having one file for each group.