Looks great! Do you have any plans to support third-party sending APIs (e.g. SES)? I see the reference to SMTP.

I've been looking for a good solution for ad-hoc email campaigns (w/ templates) and for sending "systems" emails to an audience of customers.

I currently look after lists on both MailChimp and EmailOctopus and get frustrated by the flat pricing for the size of the list and not how you engage with the list (e.g. I'd love to see: store your list for $X/mo, or pay $X + (list size * $Y) in the months when you email the list).