We've been using Mailgun for all of our email on http://lanyrd.com/ - sending messages via their REST API (and using them to receive bounces and email unsubscribe requests). It was easy to integrate and we haven't had any deliverability problems - they gave us plenty of great advice about that.
I've spent a bunch of time talking to them about email, and they really know their stuff.
I've spent a bunch of time talking to them about email, and they really know their stuff.