Add SMTP-based mailing services

[Anirban166]

D-mails, a core concept of Steins;Gate, could do with a reference implementation. But unfortunately, it wouldn't be possible to create such a service (albeit it was a thing in 2015, considering simple mail deletion) at the moment, or at least infeasible, by the current technology available. But again, neither is it required, given that it's impractical in our world.

However, we can certainly do with normal emails, so how about taking two emails as user input (strings) and sending a mail in between them? The body of the mail would be the output of the program as it currently displays (feel free to add additional context!)

Packages like gomail or go-simple-mail can be used (the later has a detailed example as well)

[harshil15999]

@Anirban166 please assign this to me