Using a Microsoft Exchange Contact to forward to Service Desk

I am setting up GitLab Service Desk on a self-managed instance (, 13.4.2, Omnibus via Docker).

For each software product we have a group in GitLab, and each group contains a support project that we will use as the service desk.

Since I don’t want my customers to need to send to,, etc. I want to create forwarders in our Microsoft Hosted Exchange so the customers can email,, etc. (Each product has its own domain.)

I set this up by creating groups (“distribution lists”) in the Exchange Admin Center, then by creating “mail contacts” for the GitLab email addresses, and then adding each mail contact to the proper group.

When I send mail to the group from an internal email address, it works properly. However, when I send mail from an external email address (such as a customer would), I get an error:

550 5.4.1 Recipient address rejected: Access denied. AS(201806281) []

The distribution group is set to allow external email:


Has anyone else been able to set up something like this?

Apparently it is set up correctly and just needed a few hours to propagate through the Microsoft infrastructure.