Incorporating Old Mail Getting Mail Washing Mail

6.3.7: Expiring Mail

Traditional mail readers have a tendency to remove mail articles when you mark them as read, in some way. Gnus takes a fundamentally different approach to mail reading.

Gnus basically considers mail just to be news that has been received in a rather peculiar manner. It does not think that it has the power to actually change the mail, or delete any mail messages. If you enter a mail group, and mark articles as ``read'', or kill them in some other fashion, the mail articles will still exist on the system. I repeat: Gnus will not delete your old, read mail. Unless you ask it to, of course.

To make Gnus get rid of your unwanted mail, you have to mark the articles as expirable. This does not mean that the articles will disappear right away, however. In general, a mail article will be deleted from your system if, 1) it is marked as expirable, AND 2) it is more than one week old. If you do not mark an article as expirable, it will remain on your system until hell freezes over. This bears repeating one more time, with some spurious capitalizations: IF you do NOT mark articles as EXPIRABLE, Gnus will NEVER delete those ARTICLES.

You do not have to mark articles as expirable by hand. Groups that match the regular expression gnus-auto-expirable-newsgroups will have all articles that you read marked as expirable automatically. All articles marked as expirable have an `E' in the first column in the summary buffer.

By default, if you have auto expiry switched on, Gnus will mark all the articles you read as expirable, no matter if they were read or unread before. To avoid having articles marked as read marked as expirable automatically, you can put something like the following in your `.gnus' file:

(remove-hook 'gnus-mark-article-hook
             'gnus-summary-mark-read-and-unread-as-read)
(add-hook 'gnus-mark-article-hook 'gnus-summary-mark-unread-as-read)

Note that making a group auto-expirable doesn't mean that all read articles are expired---only the articles marked as expirable will be expired. Also note that using the d command won't make groups expirable---only semi-automatic marking of articles as read will mark the articles as expirable in auto-expirable groups.

Let's say you subscribe to a couple of mailing lists, and you want the articles you have read to disappear after a while:

(setq gnus-auto-expirable-newsgroups
      "mail.nonsense-list\\|mail.nice-list")

Another way to have auto-expiry happen is to have the element auto-expire in the group parameters of the group.

If you use adaptive scoring (see Adaptive Scoring) and auto-expiring, you'll have problems. Auto-expiring and adaptive scoring don't really mix very well.

The nnmail-expiry-wait variable supplies the default time an expirable article has to live. Gnus starts counting days from when the message arrived, not from when it was sent. The default is seven days.

Gnus also supplies a function that lets you fine-tune how long articles are to live, based on what group they are in. Let's say you want to have one month expiry period in the `mail.private' group, a one day expiry period in the `mail.junk' group, and a six day expiry period everywhere else:

(setq nnmail-expiry-wait-function
      (lambda (group)
       (cond ((string= group "mail.private")
               31)
             ((string= group "mail.junk")
               1)
             ((string= group "important")
               'never)
             (t
               6))))

The group names this function is fed are ``unadorned'' group names---no `nnml:' prefixes and the like.

The nnmail-expiry-wait variable and nnmail-expiry-wait-function function can either be a number (not necessarily an integer) or one of the symbols immediate or never.

You can also use the expiry-wait group parameter to selectively change the expiry period (see Group Parameters).

If nnmail-keep-last-article is non-nil, Gnus will never expire the final article in a mail newsgroup. This is to make life easier for procmail users.

By the way: That line up there, about Gnus never expiring non-expirable articles, is a lie. If you put total-expire in the group parameters, articles will not be marked as expirable, but all read articles will be put through the expiry process. Use with extreme caution. Even more dangerous is the gnus-total-expirable-newsgroups variable. All groups that match this regexp will have all read articles put through the expiry process, which means that all old mail articles in the groups in question will be deleted after a while. Use with extreme caution, and don't come crying to me when you discover that the regexp you used matched the wrong group and all your important mail has disappeared. Be a man! Or a woman! Whatever you feel more comfortable with! So there!

Most people make most of their mail groups total-expirable, though.

Incorporating Old Mail

Getting Mail

Washing Mail