Another vote for Mailgun. I use them for all my side projects, monitoring, error reports, basically everything gets hooked into my FastMail account with all the right aliases I need, and it works very well.
I've never gone over my free allocation even when I have a dozen or so side projects up and testing.
Wow. Thank you guys for the suggestion. I really like that the first thing I see on the Mailgun landing page is sample code for calling the API, and the second thing I see is a pricing calculator.
I've never gone over my free allocation even when I have a dozen or so side projects up and testing.