From Elendor
Syntax: +UNMAIL <unique message ID number>
This is a command that will take back a message that you have already mailed
or posted away. Here's how it works: Every mail message that has ever been
written on Elendor is given a unique number (usually about 6 digits long).
You will see this number at the top of messages when you +read them or
+proof them in progress and also when you send/post messages it will be
displayed in the confirmation message you get. That number is the one you
need for this command. It won't let you unmail a message if it's not yours
but you need to know the ID number. Somebody who you sent it to should be
able to tell you it. Also you can unmail postings from bulletin boards
too. (Just read the message on the bboard to find out the ID number.)
Unmailing a message draws it back into your buffer so that you can use the
editing commands on it and send it again or +TOSS it. You can't unmail a
message if you are already in the process of writing one. You will need to
either +TOSS the one you are in the middle of writing or send it before
being able to unmail a previous one.
Example: +unmail 203993
(Takes back the message 203993 from everyone's mailbox and off of any
bulletin boards it was sent to and puts it in your buffer for editing.)