How to troubleshoot Diagnostic-Code: smtp; 554 5.4.6 Hop count exceeded – possible mail loop?

When someone sends an e-mail to our customers; they may receive the following bounce back and the sender in such a case might contact our customer with the following bounce back.

Bounce Back:

Reporting-MTA: dns; sfw1.apps4rent.com
X-Postfix-Queue-ID: E490CF48082
X-Postfix-Sender: rfc822; xxxxxx@xxxxxx.com
Arrival-Date: Thu, 11 Feb 2010 04:51:26 -0500 (EST)

Final-Recipient: rfc822; yyyyyy@yyyy.com
Original-Recipient: rfc822;yyyyyy@yyyy.com
Action: failed
Status: 5.4.6
Remote-MTA: dns; 192.168.168.241
Diagnostic-Code: smtp; 554 5.4.6 Hop count exceeded – possible mail loop

Solution:

The sender gets this bounce back due to a mail loop.  This is generally caused if our customer (yyyyyy@yyyy.com) has added his e-mail address (yyyyyy@yyyy.com) and more than two location in the control panel.  For example:  Our customer has added yyyyyy@yyyy.com as an e-mail address; is also a member of the distribution group called group1@yyy.com and he has setup a forwarder for his email address yyyyyy@yyyy.com to group1@yyy.com.  In such a case; when the system receives an e-mail for yyyyyy@yyyy.com; it forwards a mail to group1@yyy.com.  Now as yyyyyy@yyyy.com is also a member of group1@yyy.com; this forms a never ending loop.

Another example is that you have an e-mail address yyyyyy@yyyy.com and at the same time you have created a contact which has the same e-mail address which has e-mail address as yyyyyy@yyyy.com.

Please ensure that your e-mail address yyyyyy@yyyy.com is not added in such a fashion to a distribution group.  Also, please ensure that your e-mail address is not created as contact also.  You would not need to create a contact for your e-mail; as you have a mailbox you will be listed in GAL to your other users.

Note:   Not all cases have been discussed here.  These are some examples.  However, if people are reporting to you that they are getting such a bounce back when they send an e-mail to you; then you need to check your account and see if your e-mail address yyyyyy@yyyy.com has been added twice in the system.

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