# 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.
## **message files**
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" rung:
$ 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 --output=files tag:deleted | xargs -l 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.
##