Despite attempts to reinvent it, email is still one of the most popular ways to communicate across the internet. Developers have long been able to take advantage of Emails popularity using various libraries that support POP, SMTP and IMAP. This is fine when you have access to a publicly available web server, but for small and hobby developers this can be an unacceptable cost.
As a developer, you can figure out how to make your program connect to Facebook, Twitter, SMS, and Email. Or you can use the Embarke API and connect just to Embarke, a messaging platform that connects you to them all. You can skip learning the specifics of how to connect to each of them. The REST API's website has a five minute tutorial video on how to use this gateway to its developer tools for social communications.