Ask HN: Email Service Provider For Web Apps

I know all about companies such as Mail Chimp and aweber but they seem more for email campaigns to a group of people. Yet with each public app I create I need to add email capabilities for password resets, confirmations or notifications. Is there a company that I can integrate with that would do this for me.

So I would just call an API method saying, send an email to this email, with this template (that I preloaded in their system) and this data. Then I could use the companies email tracking capabilities, unsubscribe and other list management functionality without having to do it all on my site.