Hi all,

I built SignupScore after I went to grab one of the public disposable email lists everyone uses, and found .gov and .edu sitting on it. Apple Hide My Email too. And uk.com, which takes out every business under it. Someone opened a GitHub issue at some point and it just got merged, and nobody ever looked at it again.

That stuff is running in production at a lot of companies right now. Real people getting rejected at your signup form, and you never hear about it, because nobody writes in to say hey, I couldn't sign up.

So I did it the slow way.

What it catches:

- Disposable and temp mail domains. Roughly 200k in the corpus, every one of them reviewed

- Dynamic DNS zones, the free subdomains people spin up fresh for each signup

- Gibberish and test addresses. asdf123@, test47@, burner@. You know the ones

- Role accounts like info@, support@, admin@

- Domains that can't receive mail at all, checked live against MX rather than guessed from the name

- Typo domains like gmial.com. I hand it back as a suggestion instead of a rejection, so you can just ask the user to fix it

- Newly registered domains, if you want that as a rule. Off by default

- The same person signing up again under a different spelling of the same address

What it won't block, which is the part I actually care about:

- .gov, .mil, .edu and .int. These never enter the list in the first place

- Apple Hide My Email, Firefox Relay, DuckDuckGo, SimpleLogin and the rest. Flagged so you can decide, never auto-blocked

- Registry suffixes like uk.com, where one block takes out every business sitting under it

- Anything I haven't looked at yet. No feed can auto-merge into the corpus. Last cleanup pass I pulled 503 domains that shouldn't have been in there, and that was after the automated checks

How you use it:

- REST API, one call per signup, returns block / review / allow with the reason

- Dashboard for your own block rules and policy switches, so you're not redeploying to change a threshold

- Free tools if you just want to check one thing without an account: MX lookup, DNS lookup, blacklist check, BIMI, email authentication

- Starts free at 250 checks a month, no card

Would really like feedback, especially if you've ever had a real customer blocked by one of these lists. And the launch video is fable 5, I didn't touch a video editor once.