It is very easy to use Powershell to change the recipient type of a mailbox in Office 365, but this cannot be done using the web interface.
This can be done by using the Set-mailbox cmdlet and there are four possible types of mailbox that you can set:
In order to do this you will need to connect to 365 with Powershell and execute the Set-Mailbox command against the mailbox that you want to change. As with my other 365 posts I’ve made this super simple for you by providing all of the code based on your parameters.
Just fill in the identity value of the mailbox that you want to convert, then select the mailbox type that you want to convert it to. Then simply copy and paste the generated code to a Powershell window.
You will be prompted for your Office 365 credentials and then the change will be made.E-Mail identity of mailbox (e.g. email@example.com):
Mailbox type to convert to:
If you are converting to a “Regular” mailbox, ensure that you assign a license after you have run the conversion.