Tracking bounced messages with VERP

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Some mailing list programs, such as Mailman or Dada Mail, can be configured to track messages they send out and which then get bounced by using a special method called VERP. You can also use this method to track bounced messages and then manually unsubscribe the associated person from your mailing list.

VERP encodes each user's destination e-mail address into a custom return path address. For example, if you normally send messages with a return path of listname@example.com, and you want to send a message to member@example.org, then using normal protocols (ie, without using the special VERP method), your e-mail would be sent like this: 

Return-Path: listname@example.com
From: listname@example.com
To: member@example.org

Any such message that bounces would be sent back to the return path address (listname@example.com).

However, a message sent using VERP would look like this (only the Return-Path is different): 

Return-Path: listname+member=example.org@example.com
From: listname@example.com
To: member@example.org

Any VERP message which bounces would get returned to the listname+member=example.org@example.com address. Our mail server will silently ignore everything between the "+" and the "@", and will deliver the bounce notification to listname@example.com.

You can then handle the bounce notification in several ways:

  • You can read them manually and unsubscribe the appropriate person.
  • Mailman will automatically read these bounce messages and unsubscribe the associated user.
  • Dada Mail can be configured to automatically pick up such bounces and unsubscribe people, but it takes more effort; please see the Dada Mail documentation for full details.

Note: In order for VERP to work, you need to make sure that you send messages using a "+" separator instead of the default "-" separator. If you are using Dada Mail, be sure to edit your Dada Mail configuration file.

Note: If you are running a mailing list, please be sure to review our mailing list policy.