Unable to relay message to recipient domain - Error Please turn on SMTP Authentication in your mail client

Products

• Email Security.cloud

Issue/Introduction

Unable to relay message to recipient domain .Error Please turn on SMTP Authentication in your mail client. In Track and Trace when we run the message tracking using the failure recipient domain parameter  and check the Log view we get the below error 

Status550-Please turn on SMTP Authentication in your mail client. 550-mailx.bemtaxx.messagelabs.com [xxx.xxx.xxx.x]:15387 is not permitted to 550 relay through this server without authentication.

Log view also shows the connectivity with the recipient domain is not working and there are many delivery attempts as shown below and then connectivity is established.

Delivery attempt #12022-12-16 01:54:55 AM
Recipient server: 0.0.0.02022-12-16 01:54:55 AM

Response: 421 4.4.4 [internal] Domain Does Not Resolve2022-12-16 02:01:17 AM
Delivery attempt #22022-12-16 02:01:17 AMRecipient server: 0.0.0.02022-12-16 02:01:17 AM

Response: 421 4.4.4 [internal] Domain Does Not Resolve2022-12-16 02:16:43 AM
Delivery attempt #3 (final)2022-12-16 02:16:43 AM

Recipient server: xxx.xx.xx.xx (domain .com) 2022-12-16 02:16:43 AM

 

Please Note: domain .com here represent the recipient domain for which delivery is attempted.

 xxx.xx.xx.xx  Represent the A record of the  recipient domain for which delivery is attempted.

 

Environment

Email Security .Cloud 

 

Cause

Symantec Email.Cloud delivery servers attempt to deliver emails to the MX record of the recipient domain. Once the MX record is not available, email will be attempted to ANY records available. In the scenario presented,  the email was attempted to the A record which is not authorized to receive the mail. 

Resolution

Need to contact recipient domain administrator/owner to address the DNS issues.