6.4.5 Mail Back End Variables

These variables are (for the most part) pertinent to all the various mail back ends.

nnmail-read-incoming-hook

The mail back ends all call this hook after reading new mail. You can use this hook to notify any mail watch programs, if you want to.

nnmail-split-hook

Hook run in the buffer where the mail headers of each message is kept just before the splitting based on these headers is done. The hook is free to modify the buffer contents in any way it sees fit—the buffer is discarded after the splitting has been done, and no changes performed in the buffer will show up in any files. gnus-article-decode-encoded-words is one likely function to add to this hook.

nnmail-pre-get-new-mail-hook

nnmail-post-get-new-mail-hook

These are two useful hooks executed when treating new incoming mail—nnmail-pre-get-new-mail-hook (is called just before starting to handle the new mail) and nnmail-post-get-new-mail-hook (is called when the mail handling is done). Here's and example of using these two hooks to change the default file modes the new mail files get:

          (add-hook 'nnmail-pre-get-new-mail-hook
                    (lambda () (set-default-file-modes #o700)))
          
          (add-hook 'nnmail-post-get-new-mail-hook
                    (lambda () (set-default-file-modes #o775)))

nnmail-use-long-file-names

If non-nil, the mail back ends will use long file and directory names. Groups like ‘mail.misc’ will end up in directories (assuming use of nnml back end) or files (assuming use of nnfolder back end) like mail.misc. If it is nil, the same group will end up in mail/misc.

nnmail-delete-file-function

Function called to delete files. It is delete-file by default.

nnmail-cache-accepted-message-ids

If non-nil, put the Message-IDs of articles imported into the back end (via Gcc, for instance) into the mail duplication discovery cache. The default is nil.

nnmail-cache-ignore-groups

This can be a regular expression or a list of regular expressions. Group names that match any of the regular expressions will never be recorded in the Message-ID cache.

This can be useful, for example, when using Fancy Splitting (see Fancy Mail Splitting) together with the function nnmail-split-fancy-with-parent.