MailBounceDetector
this library detects whether a message is a bounce message.
this detects standard and qmail bounce messages.
see the unit tests for an example on how that information is exposed by the library.
Standard bounce messages
a bounce message is one that has (or is) a multipart/report; report-type=delivery-status MIME part. its comprised of two or three sub-parts:
- the human readable description of the bounce. normally this is a
text/plainortext/htmlpart. - the machine readable description of the bounce. this is a
message/delivery-statuspart. - the original message that bounced. this part is optional, and might not have the complete message. its useful to known some of the original message headers such as the
Message-Id. this is normally amessage/rfc822part.
the most important part is the message/delivery-status part; it looks something like:
Content-Type: message/delivery-status
Reporting-MTA: dns; PTPEDGE02.test.local
Final-recipient: RFC822;
email_that_does_not_exists_this_is_just_a_test@gmail.com
Action: failed
Status: 5.1.1
Remote-MTA: dns; mx.google.com
X-Supplementary-Info: <mx.google.com #5.1.1 smtp;550-5.1.1 The email account
that you tried to reach does not exist.Please try 550-5.1.1 double-checking
the recipient's email address for typos or 550-5.1.1 unnecessary spaces.
Learn more at 550 5.1.1 https://support.google.com/mail/answer/6596
om11si19081667wic.29 - gsmtp>Standard bounce messages references
- RFC6522 about the
multipart/reportpart: The Multipart/Report Media Type for the Reporting of Mail System Administrative Messages - RFC3464 about the
message/delivery-statuspart: An Extensible Message Format for Delivery Status Notifications - RFC3463 about the
message/delivery-statuspart status codes: Enhanced Mail System Status Codes
qmail bounce messages
a bounce message is one that is a text/plain (which can also be inside a multipart/alternative) MIME part, e.g.:
Date: 17 Mar 1996 03:54:40 -0000
From: MAILER-DAEMON@silverton.berkeley.edu
To: djb@silverton.berkeley.edu
Subject: failure notice
Hi. This is the qmail-send program at silverton.berkeley.edu.
I'm afraid I wasn't able to deliver your message to the
following addresses. This is a permanent error; I've given up.
Sorry it didn't work out.
<god@heaven.af.mil>:
Sorry, I couldn't find any host by that name.
--- Below this line is a copy of the message.
Return-Path: <djb@silverton.berkeley.edu>
Received: (qmail 317 invoked by uid 7); 17 Mar 1996 03:54:38 -0000
Date: 17 Mar 1996 03:54:38 -0000
Message-ID: <19960317035438.316.qmail@silverton.berkeley.edu>
From: djb@silverton.berkeley.edu (D. J. Bernstein)
To: god@heaven.af.mil
Subject: are you there?
Just checking.