Update 10/22/2025: Addition of two more FAQs.
In May 2024, we shared our Exchange Server Roadmap Update and our plans for the future of Exchange Server. Since then, we’ve been asked some questions ...
Updated Oct 22, 2025
Version 18.0
Blog Post
Nino_Bilic
Microsoft
MicrosoftThat kind of depends on what you mean by "SMTP relay". Here is what I mean:
- If you are relaying email for your Exchange Online users (like some sort of bulk delivery that you use on-prem servers for) - then you do not have additional license complications because Exchange Server licenses are covered for your Exchange Online users under the Microsoft 365 E3/E5 extended use rights Microsoft Product Terms
- If you have applications / devices etc. from on-premises that you relay for, then you should have a license for the on-prem SMTP relay server.
Apps / devices are relaying for same exo users.. From point 1, I get that we don’t need to worry about any license changes and current hybrid server license will work with SE.
so this is where is gets complicated. The apps / devices are not sending as the users but as either a shared mailbox or in most cases a noreply@ type address that does not exist. They would be mostly going to our licensed users but not coming from.
I would still think this is an acceptable scenario..correct me if I'm wrong Nino_Bilic
Now if the relayed emails are being sent to a non-accepted domain using a custom send connector or m365 outbound connector, then that would be a different scenario.
right now we have six servers in a DAG that happens to be the SMTP relay and about 30 mailboxes left on them, everything else is in the cloud, however those 6 point to the four hybrids that then relay everything into the cloud.
We’re trying to consolidate everything and rebuild the four hybrid boxes to be the SMTP relay, and move the last few mailboxes to them until they get migrated as their generics. This would allow us to be able to eliminate the six mailbox servers that are still internal.
The four hybrid boxes are only routing mail back-and-forth now. We were hoping to be able to use them as the SMTP relay as well.
We’ve seen mixed comments about using the hybrid license that’s free or if we have to buy a license for the servers like a standard edition for SE or if our existing licensing in the cloud with E3 E5 subscription covers the server license.
