Columbia MM
MM Manual


It is not always easy to know whether your message got through. If it is not returned to you as undeliverable, it probably reached the address. Some systems provide a return receipt. If mail is returned, and you don't see anything obviously wrong with the address, you can get help from the postmaster.


Some mail systems have a function that can send you a receipt when the mail is read. To get the acknowledgement, you have to include a special header in the message, return-receipt-to, with your address (or wherever you want the receipt sent). In MM the header can be created as follows:

S>user-header return-receipt-to

Whether you get a receipt then depends on the mail system where the message is received. If the system does not send receipts, the header is simply ignored.


The finger command can sometimes be useful in checking mail delivery. Firstly, it can verify that the address exists. Secondly, some (but not all) finger programs show whether the user has new mail.

jb51     Joseph Brennan       Last login Aug  1 15:27 from ttyu2 (
No new mail.


If mail cannot be delivered, it is usually returned to you, with a message indicating why. This is known as a bounce. If you do not understand what is wrong, you can ask the postmaster on your system for help. The best way usually is to send the complete bounce message to postmaster, using the forward command. You can delete the text if you like, but leave all the header lines.

The most common cause of bounced mail is simple typos. Check the address you meant to use against the address that is actually on the message being returned. There are a large number of possible bounce messages, but a few of the most common are shown below, in case you want to try diagnosing the problem.

This example shows the beginning of a bounce message. The bounce itself is from the Mailer-Daemon (mail delivery program) and the problem in this case is User unknown. The entire original message would be included after the bounce notice.

 Message 50 (977 chars)
Return-Path: <Mailer-Daemon>
Received: by (5.59/FCB)
        id AB26396; Mon, 11 Feb 91 09:18:01 EST
Date: Mon, 11 Feb 91 09:18:01 EST
From: Mail Delivery Subsystem <Mailer-Daemon>
Subject: Returned mail: User unknown
Message-Id: <>
To: jb51

   ----- Transcript of session follows -----
>>> RCPT To:<>
<<< 550 User unknown
550 Aethelred B Cooper <>... User unknown

   ----- Unsent message follows -----
Return-Path: <jb51>
Received: by (5.59/FCB)
        id AA29491; Mon, 11 Feb 91 09:18:01 EST
Date: Mon, 11 Feb 91 9:17:58 EST
From: Joe Brennan <>
To: Aethelred B Cooper <>

Problem: User Unknown.

The part before the @ sign is no good. Check for typos. It might be that the