Support sending faxes via email, e.g. 6505551212@fax.ringcentral.com

This gives programmers the ability to integrate directly to RingCentral, and not have to rely on stand-alone email applications (like Outlook, Gmail, or Microsoft Mail) or a third party (like JangoMail) to send fax requests to FaxNumber@rcfax.com. There is no flexibility to automate email sends to get faxes into RingCentral's queue, other than having users save all attachments to file and attach them manually, or contract with a third party to handle this integration. This should be a service that Ring Central provides.