The autoresponder is working. I havent tested setting a new one in outlook yet.

EDIT: Just tested it and it works as expected.

I may have discovered my issue. I have a Content Filter set to forward all messages to the new email address the customer is switching to. I also turned on Autoresponder with the intention of replying to the Senders and letting them know to update this customer's email address in their system. 

Autoresponder doesn't seem to work in this case (I've tried on two different servers). Perhaps triggering the Content filter stops all further actions... My preference would be that both the Content filter AND Autoresponder can be used simultaneously.