A few days ago, my friend Peter ask me about the process of convert an active directory user to remote mailbox in hybrid environment composed by Exchange Online and Exchange 2013 on premises. In some environment, your active directory has many users that not has a mailbox yet. But now, you need to create a mailbox for these users that response for both Exchange services. This process can be accomplish using enable-remotemailbox cmlet.

When my friend Peter tried the conversion using the enable-remotemailbox cmdlet, he received the following error:

This task does not support recipients of this type. The specified recipient </DC/OU/user> is of type UserMailBox.

The error occurs because the selected user has a local mailbox created. The enable-remotemailbox cmdlet only works with active directory users that not has a mailbox created. If the mailbox had been in use, you need to migrate it using the migration tools for Exchange online. If the mailbox was accidentally created, you can disabled it through EAC, Recipients. Next, you need to select the mailbox, then press on more and select disable.

Other way is by executing Disable-Mailbox -Identity <user> cmdlet.

After that, you can proceed to execute the enable-remotemailbox cmdlet again.

See you soon!