Delivery of emails sent through DLP CDS and ESS is failing with a 4.4.2 error.

Products

• Data Loss Prevention Cloud Service for Email

Issue/Introduction

Emails are routed through CDS for Email (DLP Cloud) for the inspection of sensitive data and forwarded to Email Security.cloud.

Although outbound emails are successfully inspected by CDS for Email, they fail to be delivered to recipients, resulting in the following message:

Reason: [{LED=451 4.4.400 Error communicating with frontend host or destination host. -> 421 4.4.2 Connection dropped due to ConnectionReset};{MSG=};{FQDN=SMTP address };{IP=<x.x.x.x>};{LRT=MM/DD/YYYY hh:mm:ss A/PM}]. OutboundProxyTargetIP: x.x.x.x. OutboundProxyTargetHostName: SMTP address

 

Environment

Integration between Email Security Service (ESS) and Cloud Detection Service (CDS) for Email (Data Loss Prevention) is active.

Cause

The Email Security Service (ESS) is rejecting messages from the Data Loss Prevention (DLP) system due missing Outbound Routes.

Resolution

Essentially, Need to an Outbound Route under Hosted Email Services ('Platform' > 'Outbound Routes') to accept messages from DLP.

Refer to Knowledge article from Email Security.cloud for resolution of issue.