check-if-email-exists

I started with open-source. I initially created https://github.com/reacherhq/check-if-email-exists, after some years it got to ~50 stars and nice overall feedback, that's when I thought of a SaaS wrapper on top of it. So a possible path is "idea -> open-source -> monetize". I find the first arrow to be easier to execute than a direct idea to monetization leap.

I run an open-source [1] email verification API, called Reacher. I managed to hit 10k ARR this year (1st year). It's written in Rust, self-hostable, and does not use a DB of emails (like some competitors do). Landing page: https://reacher.email. [1]: https://github.com/reacherhq/check-if-email-exists

GitHub issues like this one warm my heart: https://github.com/reacherhq/check-if-email-exists/issues/91 Identifying something that needs doing, especially when you have no idea how to do it, is a bold skill. Too often have I seen engineers be reluctant to open an issue because they don’t know how to implement it, technically. I still do it, myself. If you need it then you’ll find a way. The converse is also true: losing focus by filing tasks and procrastinating on features because you know how to build them, not because you actually need them to move your business / project forward.

Interesting. So if they are doing this are they violating CANSPAM? EDIT: Looks like they are indeed doing the SMTP method: https://github.com/reacherhq/check-if-email-exists/blob/a052... I also found a similar, much bigger service here that appears to have been around for a while: https://emailverification.whoisxmlapi.com/api

If you want to know the "how?" as I did - code is here, specifically https://github.com/reacherhq/check-if-email-exists/blob/mast... tl;dr, According to RFC 5321, `RCPT TO` command succeeds with 250 and 251. So email is valid if you get to this part of the protocol and receive the response.

That's what this project does too: https://github.com/reacherhq/check-if-email-exists/blob/a052...