Azure recently introduced PIP - Public IPs that can be assigned to Virtual Machine instances, however it appears that there is no way to assign a PTR record to that IP so that a reverse DNS lookup will be successful. Here are the instructions to assign a PIP to an Azure VM:
https://azure.microsoft.com/documentation/articles/virtual-networks-instance-level-public-ip/
We have VMs on Rackspace Cloud running SMTP services that I'm trying to duplicate on Azure, but there appears to be no way to assign a PTR record for your Azure PIP. As a result, we are unable to provide our own SMTP service on Azure. Rackspace Cloud assigns a public IP address, and allows you to edit their DNS PTR records for that IP address and assign it to your service. Is there any way to do something similar with Azure?
BTW: SendGrid and Amazon SES are not an option. We've been running E-mail servers for decades responsibly, unless we can get a VM with a public IP and DNS setup properly, Azure isn't a viable option.