From Elendor
There are seven basic commands to handle deletion of mail messages and
bulletin board posts:
See HELP +delete for marking messages for deletion.
See HELP +undelete for saving messages marked for deletion.
See HELP +clear for purging messages marked for deletion.
See HELP +deleted to list all messages marked for deletion.
See HELP +expunge for destroying messages and posts (dangerous).
See HELP +toss for deleting a mail message in progress.
See HELP +unmail for deleting a mail message previously sent.