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 address was good once, but the person's account has expired. One way to get help is to send a message to postmaster at the remote host, asking whether there is an address for the person you want to reach; for best results supply the full name and affiliation.

Problem: Host Unknown.

The part after the @ sign is unknown to the mail system. Check for typos. Sometimes the address is good but your own host does not know how to locate it. For help, send the bounce notice to postmaster at your own site. They may be able to spot an error in the address or find a way to reach it.

Problem: Mail Could Not Be Delivered.

The message could not deliver mail for 3 days means that either the host or the network connection to it was down. The mail program automatically tries to send repeatedly over a three-day period, and then gives up and sends back the message. The address itself appears to be valid, at least as far as the message travelled; whether it is completely valid cannot be determined. You could try sending again, or use some other method like a telephone call. Ask postmaster at your site whether there is any known problem.

Problem: The message is too long.

Some systems refuse mail that they consider to be too long. 100k is a typical limit. BITNET as a network has a limit of 300k, and messages over 100k may be delayed until overnight or weekends. You could try breaking up the material and sending as multiple small messages of 50k or less.

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