SMTPNOTE command: Undelivered notes

When SMTP cannot deliver a piece of mail, a nondelivery note explaining the reason for nondelivery is sent to the sender. Nondelivery can occur for several reasons, such as the destination host is unreachable, or the recipient does not have a user ID on the destination host. If a note cannot be delivered, the body of the original piece of mail is returned as part of the nondelivery notification. For an example of a nondelivery note, see Figure 1. The nondelivery note is shown in bold.

Figure 1. Example of a nondelivery note

Date: Mon, 9 Mar 92 08:23:54 EST
From: SMTP@MVS1.ACME.COM
To:   DANIEL@MVS1
Subject: Undeliverable Mail
MVS1.ACME.COM unable to deliver following mail to recipient(s):
      <MATT@SMTP-GATEWAY.IBM.COM>
MVS1.ACME.COM unable to connect for 3 days to host:
      SMTP-GATEWAY.IBM.COM
       ** Text of Mail follows **
Date: Mon, 9 Mar 92 08:22:36 EST
From: <DANIEL@MVS1.ACME.COM>
To:   <MATT@SMTP-GATEWAY.IBM.COM>
Subject:   ACME iron birdseed

Matt,

The shipment of ACME iron birdseed was shipped last Thursday.  Please
advise me if you have not received it, and I’ll try to track it down.
Also, your ACME giant rock catapult is on back order; another customer
bought the last one yesterday.

Daniel

If a recipient is unknown at the destination host, the destination host does not accept the mail for delivery, and a nondelivery note is forwarded to the sender. For an example of an unknown recipient note, see Figure 2. The unknown recipient note is shown in bold.

Figure 2. Example of an unknown recipient note

Date: Mon, 9 Mar 92 13:32:12 EST
From: SMTP@MVS1.ACME.COM
To:   DANIEL@MVS1
Subject: Undeliverable Mail
MVS1.ACME.COM unable to deliver following mail to recipient(s):
      <GEORGE@SMTP-GATEWAY.IBM.COM>
MVS1.ACME.COM received negative reply from host:
      SMTP-GATEWAY.IBM.COM
       ** Text of Mail follows **
Date: Mon, 9 Mar 92 08:22:36 EST
From: <DANIEL@MVS1.ACME.COM>
To:   <GEORGE@SMTP-GATEWAY.IBM.COM>
Subject:   Your retirement

George,

I recently learned that you will soon be retiring.  I just wanted to
wish you best of luck and thanks for all the great work you’ve done.
You were a great asset to your company, and I’m sure they will miss you.

Daniel