Emails are stuck in the Messaging Gateway's outbound queue with "421 4.7.7 [internal] Unable to process message at this time"

Products

• Messaging Gateway

Issue/Introduction

Emails are stuck in the Symantec Messaging Gateway's (SMG) outbound queue with the messages "421 4.7.7 [internal] Unable to process message at this time".

Brightmail Engine Logs:
Error while attempting to resolve sender address: <SENDER'S EMAIL ADDRESS>.
DDS client: XML-RPC call returned fault 800206 - Attempt to authenticate to data source failed: <DDS SOURCE>

Directory Data Source:
- [1548573671475] 800206 com.symantec.sms.dds.api.exception.DataAccessAuthenticationException: Attempt to authenticate to data source failed: <DDS SOURCE> at com.symantec.sms.dds.dao.SpringLDAP.ExceptionInspector.translateException(ExceptionInspector.java:147)

Cause

The SMG was unable to authenticate to the configured Directory Data Source (DDS) and was unable to resolve the sender's email address.

Resolution

Verify that the DDS Administrator Credentials (Administration -> Settings -> Directory Integration -> -> LDAP Server -> Test Login) are correct.  If the credentials are incorrect, provide a valid set of administrator credentials.