Sure! A great example is the actual code we are using now. We are based on the Laravel framework so here is the driver code laravel uses. https://github.com/lar

Sure! A great example is the actual code we are using now. We are based on the Laravel framework so here is the driver code laravel uses. https://github.com/laravel/framework/tree/5.2/src/Illuminate/Mail/Transport https://github.com/laravel/framework/tree/5.2/src/Illuminate... You'll notice there is an abstract class "Transport.php" which declares certain methods (via the Swift_Transport interface class) that the "MandrillTransport", "MailgunTransport" and the "SesTransport" must all implement. > I think case in point, free is not forever in SaaS business. Our account & our customers' accounts were all paid. Some of them send up to 500,000 emails each per month. I would have been fine with them getting rid of the free tier, its the TOS change for marketing emails that killed our use with them.