I have a tenant with a single Exchange Online (Plan 1) mailbox and a shared mailbox that was forwarded to an external address. This worked fine until the Exchange Online mailbox was remove and only a single shared mailbox remained.
Is my conclusion that a tenant needs an Exchange Online license to make a shared mailbox work?
Yes, you will need at least one Exchange license, otherwise the Exchange workload as a whole will get deprovisioned. The shared mailbox itself does not need a license, generally speaking.
Hi Vasil, thanks! That is interesting; never knew this. I cannot find written sources about this, do you have some references on this behaviour? I have to register it in our procedures.
It's not about shared mailboxes, it's about using the Exchange Online service as a whole. You need at least one valid license for that, if you don't have such any feature dependent on the service will not be available, shared mailboxes included.
