Microsoft 365 Copilot seems to require Exchange Online mailboxes, despite this not being listed as a requirement

Question

As the title says, Microsoft 365 Copilot is broken when your mailbox is hosted on-premises.

Reviewing https://learn.microsoft.com/en-us/microsoft-365-copilot/microsoft-365-copilot-requirements, there is nothing that says hosting your mailbox on Exchange Online is required. However, the "chat" interface at https://www.microsoft365.com/chat is useless without it (will not work at all). Other functionality like within word documents does work, so I know the licensing is good.

Moving a user to Exchange Online solves it immediately. See screenshots of errors and browser errors pointing to an outlook.office.com URL and authentication failing.

The only breadcrumb of evidence i can find is here, where it says "For content search, because user prompts to Copilot and responses from Copilot are stored in a user's mailbox, they can be searched and retrieved when the user's mailbox is selected as the source for a search query."

So it seems the documentation is missing this key piece of info for functionality here. I have a support case open, but figured I'd help others who may hit this. This is a long-running theme unfortunately, that random M365 services simply do not work in a hybrid email setup where some users have mailboxes on-premises, and MS product teams just assume everyone has Exchange Online, building core dependencies into their products without documenting it.

Thanks in advance.

Answer 1

Finally got an answer here after a month of waiting:
"Engineering has responded today on this case and confirmed that users without Exchange Online Mailboxes are currently having this issue/behavior with Copilot. They are working on fixing this but there is currently no available time frame on when that will be completed"

Answer 2

Please update us when you hear from Microsoft. Thanks for posting this.

Answer 3

This appears fixed now, with a new pop-up authentication. My test user without an exchange online mailbox can now use this.

Answer 4

Hello m49808. Do you have any support ticket number that you could share so when I open mine I could point to yours? Thank you