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# Message exclusion and deletion

An important principle of notmuch is that it does not modify your mail
(with the one exception of
[[maildir flag syncing|howto/#sync_maildir_flags]]).  A question that
frequently comes up, though, is how users can delete messages.  While
notmuch does not support, nor ever will, the deleting of messages,
notmuch has a couple of nice features that allow users to handle
excluding unwanted messages in a sensible way.

## <span id="exclude">**message exclusion**</span>

Notmuch has the ability to exclude message with certain tags from
search results.  A common usage is to exclude "deleted" or "spam"
messages so that they don't clutter your search results.  To enable
excludes, use the config utility:

        $ notmuch config set search.exclude_tags deleted spam

This will cause messages with the "deleted" or "spam" tags to be
excluded from search results.

It is still possible to find messages with excluded tags, though, by
manually including the excluded tag in your search:

        $ notmuch search from:foo and tag:spam

This will find messages from "foo" with the tag "spam", even though
"spam" is an excluded tag.

## <span id="files">**message files**</span>

Notmuch makes it very easy to access the underlying mail files
associated with specific search terms using the "file" output format
of notmuch search.  To find all message files associated with the tag
"foo" run:

        $ notmuch search --output=files tag:foo

This will output the paths to all message files with "tag:foo", one
per line.

This is useful in a number of different ways.  For instance, it could
be used to train a spam filter:

        $ notmuch search --output=files tag:spam | sa-learn -f -

It can also be used to purge mail files from disk:

        $ notmuch search --format=text0 --output=files tag:deleted | xargs -0 --no-run-if-empty rm

Make sure you run "notmuch new" after the last command so the database
becomes aware that the files have been removed and can remove the
corresponding entries from the index.

## <span id="recipe">**putting it all together**</span>

So if you want to add message deletion to your work flow, here's a
procedure:

* Add exclusion for messages with the "deleted" tag:

        $ notmuch config set search.exclude_tags deleted

* In emacs MUA use keybinding `k d` to add a "deleted" tag to messages
  that you want to delete.

* And, finally, if you _really_ want the messages purged from disk,
  you can delete them manually with:

       $ notmuch search --output=files tag:deleted | xargs -l rm

## <span id="exclude">**killing threads**</span>

In a [[hook|manpages/notmuch-hooks-5]]

    notmuch tag +muted $(notmuch search --output=threads tag:muted)"

New messages in the thread get the muted tag. Make muted an excluded tag.
To kill a thread, tag it with muted, run notmuch new.