I am in the process of moving my Email domains from one Office365 plan (a Professional) to an Enterprise Plan. During the move, i set up some Email Aliases for older email addresses, which are still being used, but i dont send a lot of email from. But if i do need to send emails from these addresses, with the help of Powershell, I managed to set it up. The full details are listed on “how to send as an alias in Office 365”. It works perfectly! And, as a bit of shamless self promotion, if you are interested in Office365, why not drop me a mail at Tiernan at LimitedSlipNetworks dot com and i can set you up with a trial and more information.