NDR(Non-Delivery Receipt) emails created by Symantec Messaging Gateway are rejected by Qmail with an error: 451 See http://pobox.com/~djb/docs/smtplf.html.

Products

• Messaging Gateway

Issue/Introduction

If the receiving MTA is using Qmail and receives an NDR (Non-Delivery Receipt) email from Symantec Messaging Gateway(SMG), the NDR e-mail is always "451 See http://pobox.com/~djb/docs/smtplf.html." error and it keeps accumulating in the mail queue and cannot be delivered.

 

Environment

Currently supported version of SMG

Cause

Qmail does not like bare LF(line feed) as described in "https://cr.yp.to/docs/smtplf.html". (This is an article from an external site that is not Broadcom's site.)

If the Bounces Notifications Text is not customized on SMG, the bare LF (line feed) will be included in the NDR (Non-Delivery Receipt) email from SMG.
Therefore, Qmail will return an error "451 See http://pobox.com/~djb/docs/smtplf.html." and will not receive the NDR (Non-Delivery Receipt) mail.

Resolution

We plan to fix this in a future version of SMG, but have not yet decided on the version or timing as of yet.

In the meantime, if you see this happening, please customize the Bounces Notifications Text on the SMG to avoid the error.

Here is how to change the Bounces Notifications Text:

Login to SMG portal and go to 
Administration > Configuration > host > SMTP > Advanced Settings

In the Bounces Notifications Text section, customize the Text body message.
Then click Continue button and click Save button to save the configuration.