Services you should be using: MailGun

https://mailgun.net/

I've used MailGun in two of my projects, and I highly recommend it.

- very simple, RESTful API

- great documentation

- superb technical support straight from the developers

- unbeatable pricing

So if your application needs to send or receive emails, try MailGun.

Disclaimer: I'm not associated with MailGun in any way, just a fan.