Emails sent from the upstream cloud email provider are not accepted for delivery to the DLP Cloud Email Service.
"Google tried to deliver your message, but it was rejected by the server for the recipient domain"
NDR received by sender:
Technical details of temporary failure:
The recipient server did not accept our requests to connect. Learn more at https://support.google.com/mail/answer/7720
[<Customer-Cloud-Detector-ID>.ds.dlp.protect.symantec.com <IP-address-for-same>: timed out]
In this case, the mail route to the DLP Cloud Email Service had been misconfigured in the Google Gmail™ for Work setup.
It is necessary that the port specified for the DLP Cloud Service to receive messages should be 25.
Note, there is a related issue, for DLP Cloud Service and Prevent customers who forward their messages to Email Security.cloud - for a technical article on that issue, see link to TECH236455 in related articles.
The IP address for routing to DLP Cloud Email should be provided in the "Welcome Email" sent to customers who have successfully applied for server provisioning.
These details should be part of the "mail route": Settings for Gmail > Advanced settings:
<Customer-Cloud-Detector-ID> : 25