Email messages sent to Exclaimer Cloud are not being delivered (or delivery is delayed) and the Microsoft 365 message trace shows an error similar to this:
Typically, this scenario occurs if the Mail Routing options in Exclaimer Cloud are configured to return messages to the Sender Domain. This configuration tells Exclaimer Cloud to perform a lookup for each processed email, passing the processed email back to the server(s) specified within the sending domain name’s MX records.
Follow these steps to resolve the issue:
- Log into the Exclaimer portal (portal.exclaimer.com) and Launch your subscription.
- From the left-hand pane, click Configuration, then select Manage Mail Flow.
- In the right-hand pane, under Mail Routing Domain, are the relevant options.
- In Domain Name, enter the .omnicrosoft.com domain name - this can be located in the Domain list in the Microsoft 365 Admin Center. This setting is important, and an incorrect domain can result in mail flow issues.
- Click SAVE to save the changes made.
NOTES: The MX record for the Domain name (in the Mail Routing settings) should specify a single Exchange Online Server for your Microsoft 365 tenancy.
- To check the MX record for your own Domain name, use a DNS lookup tool, such as MXToolbox.
Example showing Exclaimer's domain: