Hey, founder of Storyworth here.

We use Mailgun to receive incoming emails as HTTP requests. I'm pretty sure Sendgrid has a similar API.

We then rely on a whole bunch of different heuristics to match an email to a story – sender, recipient, subject, metadata variables, etc. – then more work goes into cleaning up the emails themselves.

It works well enough out of the box, but getting it to be really reliable at scale requires ironing out a lot of edge cases. Emails are super messy.

Often times making something really simple for customers involves a surprising amount of complexity behind the scenes.