I am receiving unsolicited mass mailed spam coming out of your servers. Of which your own EULA stands strictly against. You also do not have any means for someone who isn't an azure.com customer to report your customers who are abusing your services. This leaves very few options.

The best option to solve these particular problems is to allow anyone outside of your services to enter their email address into a private database and then you initiate a full block from all of your customers to send them any email through the cloudapp.azure.com servers.