Do I need a EOP license for an on-premises mailbox of a user with M365 licenses?

Question

Dear all,

I have searched, but am not getting a 100% clear answer to this.

• I have a Hybrid Exchange Environment, but all mail routing is still done via on-prem Edge Transport servers.
• All mailboxes are on-prem.
• All users already have an E1 or E3 license AND an O365 Defender Plan 1 license.

I want to cut out the Edge Servers and have EOL handle incoming and outgoing mail (as a first step). Now my question is: I want to make sure EOP is doing it's thing. Microsoft says that I might need EOP licenses for on-premises mailboxes. Nobody can tell me though if I do.

Do I indeed need EOP licenses for on-prem mailboxes (for users that technically have an EOP license - if their mailbox was in the cloud), or don't I because - again - technically the users have an EOP license, but they are just not yet migrated to the cloud.

My hunch is that this remark is made for on-prem mailboxes of unlicensed M365 users, for which I can imagine Microsoft would want to see some money for their services. But apparently you have to be a rocket scientist to understand Microsoft's licensing model ;-)

Thanks for any help! :-)

Answer 1

Hi, @Michel Boks

From your description, I understand that you want to simplify mail routing by eliminating on-premises Edge Transport servers and ensure that EOP is properly configured for on-premises mailboxes.

EOP can be configured to protect your messaging environment and control mail routing if you have a mix of on-premises and cloud mailboxes. EOP is included with both E1 and E3 licenses, so you don't need to purchase additional standalone EOP licenses for on-premises mailboxes in a hybrid setup.

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Answer 2

You should be fine with any E1/E3 licensed users. But as with all licensing related questions, best talkto your local Microsoft representatives.