Support conversion to shared mailbox for synced users
Currently a mailbox for a synced user can be converted to shared in EAC. This results in a corrupted mailbox object and an Azure AD object that still requires a license. See https://support.microsoft.com/en-us/kb/2710029. Customers need to move the mailbox to on-premises Exchange, convert it to shared and then move the mailbox back to Exchange Online. This process can be cumbersome and even worse, if customer is not aware of this issue the shared mailbox will be removed after the grace period expires.
It should be supported to convert a mailbox to shared for a synced user in Exchange Online, or customers should be prevented from doing this and ending up in a bad situation by removing the 'Convert to shared' option in EAC for synced users.
Microsoft is still advising to onboard mailbox and convert and sync back....
Why is this still not solved. Looks fairly easy to sync the required attributes back to Exchange.
Daniel Mueller commented
There is a quick fix: Just assign a license to the synced user with the shared mailbox, then remove the license again and it will change back to normal. Or assign a license before you convert the mailbox to shared an remove the license.
Still, this issue should not appear, 3 votes.
Phil Williams commented
I have a variation on this issue that is driving me mad!
Basic Hybrid setup not full
I create a brand new Shared mailbox in O365 and configure it. Everything is fine.
Then when the next sync hits a new 'in cloud' unlicensed user appears in the Active users view with a name that matches my new shared mailbox.
Is this expected and OK or are my shared mailboxes going to vanish after the grace period?
account does not exist ii AD and never has... so what's happening here ?
Marco Moretti commented
We have the same problem. In Exchange Online (Hybrid Deployment) we need to convert a shared mailbox to regular mailbox (with license) and viceversa but the only solution suggested is offboarding the mailbox, convert onpremise and re-onboarding.
For us in an enterprise environment, this is not acceptable because some mailbox are large 15-20 Gb and this conversion should be done several times a year.
Timo Lindenschmid commented
You can use powershell/ADSI to modify the recipient display type AD attribute on prem from shared to user and vice versa, after sync the mailbox will be converted accordingly automatically by Exchange.
Drew Lanclos commented
This only applies to hybrid deployments. It works fine if you're not hybrid.
The shared mailbox is still unfortunately tied to a dirsync'd user and so you can't disable dirsync for that user or the mailbox goes bye-bye...