Valid messages blocked at Messaging Gateway due to no sender and no reverse DNS

Products

• Messaging Gateway

Issue/Introduction

Legitimate emails are being stopped by Symantec Messaging Gateway (SMG) due to the following conditions:

• No valid sender in the envelope
• IP address the message is coming from has no valid reverse DNS entry

Message Audit Log entries will show:

Rejected message by MTA, RDNS record fro connecting IP has no matching 'A' or 'MX' records

Resolution

Recommended Solution:

The sender domain must add either an 'A' record or 'MX' record that returns the IP or IPs in question to their domain.

 

Workaround:

Disable DNS Validation for situations where RDNS exists, but 'A' or 'AAAA' does not match.

 

For both solutions: see Error: "554 5.7.1 Rejected message by MTA, RDNS record for connecting IP has no matching 'A' or 'MX' records"