Sometimes you're sending via SMTP, sometimes via MailGun. If you don't remember to call GetMailPolicySingleton()->SetSendingMechanism() before every email.send(

Sometimes you're sending via SMTP, sometimes via MailGun. If you don't remember to call GetMailPolicySingleton()->SetSendingMechanism() before every email.send() you end up using whatever policy was set last.