Generic interface around receiving and sending email

The Email service can be AWS SES, Mailgun, Postal or any other.

You can find example implementation using Mailgun's service here

The code inherits the same principle as datastore/sql pluggable interfaces. In this case this interface must be implemented by your custom SMTP handler:

go get github.com/mailio/go-mailio-mailgun-smtp-handler

type SmtpHandler interface {
	// ReceiveMail is a method called on the specific ESP handler webhook implementation
	ReceiveMail(request http.Request) (*types.Mail, error)
	// SendMimeMail returns generated message id or error
	SendMimeMail(mime []byte, to []mail.Address) (string, error)
}