Update 11/13/2023: We added new information on how to know when this change is released to your organization.
Today, we are announcing an update to our requirements for SMTP relay through Exchange ...
Updated Feb 22, 2024
Version 19.0
Blog Post
At this point we are using Mimecast for our smarthost for our MX record.
I have been trying to set up an smtp relay (internal printers etc) and can't determine the method I should be using. Most instructions say point to my current MX record. That MX record points to Mimecast and I had "wanted" to send internal smtp mail direct to Exchange.
I'm really unsure of method 1 or 2. So far I'd tried creating an internal user for authentication and using "that" address to send mail. The address I was using was smtp.office365.com and with port 587 and the credentials of the user I created.
I'm getting credential errors on the copier I'm testing with but I doubt it. So does this work or without my mx pointing to exchange directly (which seems more traditional) can I relay internal smtp to Exchange online. I can get smtp relay to work through mimecast so I am in business but my boss prefers going direct to Exchange for copiers et al.