Mautic bounce emails - Delivered to IMAP bounce folder but with empty Return-Path header

Product Support
1

Your software
My Mautic version is: 4.1
My PHP version is: 7.4.3
My Database type and version is: 10.3.31-MariaDB

Your problem
My problem is: Bounce messages using reply-to format are delivered to the configured bounce IMAP folder. e.g. Return-Path: bounce+bounce_619322718d3e9251078198@domain

Once the bounce message is delivered to the IMAP inbox what header is read to update contacts? Is it the Return-Path header? If so i my case the Return-Path is being stripped either by the Postfix MTA or IMAP Smartermail server as on delivery the header is empty e.g. Return-Path: <>

Has anyone seen this before and know where to look next?

2

Dean,
I’m not sure what part of the header is read by Mautic, but my bounced emails were not read either.

This is how I solved it:

  1. In my iReadMail installation I have an email account accessible from RoundCube.
  2. Create a subfolder to Inbox, i called it bounces
  3. Create a filter to collect all the incoming bounces emails in the subfolder called bounces
  4. Go to mautic / configuration/email, configure mautic imap to check the email account from iRedMail, set mautic bounced to check the bounced subfolder.
3

Yes that’s how mine is also setup using Mautic’s monitoring of the IMAP bounce folder with cron to fetch the bounce messages. It seems the Return-Path is used to set the To: address for the bounce email message and is removed by the recipents mail server.

“Only the recipient’s mail server is supposed to add a Return-Path header to the top of the email. This records the actual Return-Path sender during the SMTP session. If a Return-Path header already exists in the message, then that header is removed and replaced by the recipient’s mail server.”

  1. The return-path header is set by Mautic server as “youremail+bounce_receiver-email-id@your-domain.com”
  2. Email bounced message is sent back using the Return-Path header address. The receiver SMTP sets a new Return-Path or in this case removes it.
  3. Mautic then uses ??? header to set the contact as bounced “do not contact”. Is Mautic using the To: header which was set using the Return-Path address?

Return-Path: <>
Received: from app.domain (app.domain [XX.XX.XX.XX]) by mail.otherdomain with SMTP
(version=TLS\Tls12
cipher=Aes256 bits=256);
Fri, 19 Nov 2021 17:32:10 +0800
Date: Fri, 19 Nov 2021 17:31:36 +0800 (HKT)
From: MAILER-DAEMON@domain (Mail Delivery System)
Subject: Undelivered Mail Returned to Sender
To: bounce+bounce_61976e9a4d2b4763769789@domain

4

Anyone know which header Mautic uses to detemine bounced contacts using IMAP method? That is the when Mautic cron fetch reads the IMAP folder configured under Settings > Configuration > Email Settings > Monitored Inbox Settings > Bounces

The bounce managment page does not make this clear. Bounce management | Mautic

Note that Mautic makes use of “append” email addresses. The return-path or the list-unsubscribe header will use something like youremail+bounce_abc123@your-domain.com . The bounce or unsubscribe allows Mautic to determine what type of email it is when it examines the inbox through IMAP.

5

Ok solved by restarting Mautic and Postfix server. I think Postfix had not reloaded it’s main config file.

The header To: is being read by Mautic now to process boucnes and contacts tagged and added by filter to the bounced segment.

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