Unable to deliver to 3rd party domain generated Error code : 554 5.7.1 We do not relay

Products

• Email Security.cloud

Issue/Introduction

When using Email Security.cloud services you may encounter an NDR code 554 5.7.1 We do not relay when trying to send an email to a 3rd party domain. 

Environment

Email Security.cloud

Cause

This Bounce back error code  554 5.7.1 We do not relay is mainly caused by a DNS misconfiguration at the recipient side or an explicit policy in place.

Resolution

The Administrator of the recipient domain should check the following :

1 - The Public Domain DNS configuration is properly checked, in certain situations you would find MX issues such as duplicated entries or wrong MX priorities. 

2 - The mail server receiving external traffic is allowing the connection on SMTP port 25, this is mainly checked at the Firewall level.

3 - Remove or review any explicit traffic rejection policies, if these were set to drop certain sender's email traffic.

4 - In certain scenarios, we would advise the 3rd party domain's Admin to check if our IP Ranges are not blocked and should be permitted.