Forum Discussion
Having domain email addresses outside of Office 365
It really boils down to what features they will need access to. You can have as many unlicensed users as you want, and you can even get them access to some services without assigning a license. However if they want to send messages using O365, they will need a license.
To clarify a bit, My small company has two users now on O365 BE, with our domain setup in O365. So I'm not piloting.
And I work with a few other small companies wanting to do this also if possible, so I'm the test-case.
None of the O365 account features would be needed for the emails not using O365. They would use their existing email clients (Outlook, Win 10 Mail, etc.) to access their IMAP accounts.
I had previously tested Forwarding from our email accounts (at our web hosting company) to both O365 account and an Outlook.com account. With Forwarding setup for two different email accounts, a high percentage of the emails forwarded did not show up in the O365 inbox. I'd be afraid tell a customer he can depend on all of his mail being delivered to the O365 account, and by the way, they would have to keep the mail server emptied manually, and separately.
I just thought it may be possible.