When you try to open a new mailbox for an Office 365 users you get the
following error;
"This user's on-premises mailbox hasn't been migrated to Exchange
Online. The Exchange Online mailbox will be available after migration is
completed."
AD Connect is configured to sync users, groups and passwords from the
existing Active Directory (SBS 2011), however the option for “Exchange Hybrid
Deployment” was not selected on purpose. This is because in this particular
case the migration was for 6 users, therefore a PST export/import was done to
migrate the e-mails, contacts and calendars.
The root of the problem is because the Active Directory attribute msExchangeMailboxGuid is being synced
to Azure AD in Office 365, when it’s not required.
You have to edit a configuration inside AD
Connect (it’s actually FIM 2010 R2 under the covers). To open the configuration
panel for FIM, browse to C:\Program
Files\Microsoft Azure AD Sync\UIShell and launch miisclient.exe.
Click Connectors
and select the connector for your local Active Directory and choose Properties.
Click Select
Attributes and scroll until you find msExchangeMailboxGuid, if you have the
same problem as me this will be selected. Simply disable this attribute.
You then have to delete the old reference to the
msExchangeMailboxGuid from the FIM Connector Space. To do this select the
Active Directory management agent (also known as a “connector”), and choose Delete. Read the next part
properly.
Ensure that Delete
Connection Space Only is selected and click OK.
It will ask you to confirm you want to delete
data from the connection space, click Yes.
If you did delete the entire connector, you could provision again by
running the AD Connector wizard. This is fine if you have not made any major
modifications to your AD Connect configuration.
Use the following PowerShell command to force an
entire sync across AD Connect;
Start-ADSyncSyncCycle
-PolicyType Initial
You should notice updates when the Operations
complete.
Now if you return to Office 365, you should see
the following.
