Connections to the Symantec Messaging Gateway (SMG) are failing due to errors with the SMG's capability to use Reverse DNS (RDNS)

• 554 5.7.1 Rejected message by MTA, RDNS record for connecting IP does not exist
• 554 5.7.1 Rejected message by MTA, RDNS record for connecting IP has no matching 'A' or 'MX' records
• 554 5.7.1 Rejected message by MTA, EHLO domain does not exist in DNS
• 553 5.1.8 Rejected message by MTA, MAIL-FROM domain does not exist in DNS

Messaging Gateway 10.x or later

The inbound message is failing reverse DNS checks enabled in the SMG.

Perform a lookup of the connection IP address in Message Audit Logs to verify specific error.

Below are the errors, with links to articles with specific solutions for each:

• 554 5.7.1 Rejected message by MTA, RDNS record for connecting IP does not exist
• 554 5.7.1 Rejected message by MTA, RDNS record for connecting IP has no matching 'A' or 'MX' records
• 554 5.7.1 Rejected message by MTA, EHLO domain does not exist in DNS
• 553 5.1.8 Rejected message by MTA, MAIL-FROM domain does not exist in DNS