Exchange 2013 - Why does deleteing a mailbox delete the AD user?

Hi,

I've put up a fresh 2013 server installation (on 2012 server).

I want to delete a Mailbox and create a new one - but the Delete of the mailbox deletes the linked AD entry too. Is this the way its meant to work?

I tried again and the EAC mailbox delete indeed wipes out the AD user object.How do you delete just the mailbox?

Thanks.