How to Block Disposable Emails and Fake Signups in Node.js & Python

If you offer free trials or starter credits on your SaaS, you've probably seen users abuse temporary emails to reset their limits endlessly.

The Problem with Static Lists

Most developers start with static disposable domain lists. However, new throwaway domains pop up every single day, making static blocklists outdated within weeks.

A Better Approach: Multi-Factor Risk Scoring

Instead of a simple black/white list, checking multiple domain signals at signup provides much better protection:

1. MX Record Validity: Ensures the domain can actually receive mail.
2. Domain Age: Identifies freshly registered throwaway domains.
3. Disposable Patterns: Matches heuristic fingerprints of temporary mail services.

Open-Source Starter Repo

I packaged this logic into a lightweight wrapper and published sample code for Node.js and Python.

Check out the full repository and implementation examples here:
👉 signup-email-risk-checker on GitHub

Feel free to star or fork the project if you find it helpful for your auth flows!