Half Your Free Trial Signups Are Fake: Here's How to Fix It

MAYNO — Fri, 17 Apr 2026 20:06:35 +0000

The Problem Every SaaS Faces

Fake signups from disposable emails are killing your metrics. Someone signs up with throwaway@mailinator.com, uses your free trial, and vanishes.

Why It Matters

Wastes customer success time
Inflates your user count (fake growth)
Costs you money (server resources, email sends)
Makes your analytics useless

The Solution: Email Risk Scoring

Instead of just validating syntax, check:

Is it from a disposable provider? (mailinator, guerrillamail, etc.)
Does the domain have MX records?
Free provider vs business email?

What Good Email Validation Detects

A proper email risk scorer checks multiple signals:

Disposable domains: Is it from Mailinator, Guerrilla Mail, or 500+ other temporary providers?
MX records: Can the domain actually receive emails?
Provider type: Free (Gmail/Yahoo) vs Business (company.com)?
Role-based emails: Generic addresses like info@, admin@, noreply@
Risk level: Low, Medium, or High

How to Implement It

Option 1: DIY Solution (Free, But Manual)

# Use the GitHub disposable-email-domains list
import requests

DISPOSABLE_DOMAINS = requests.get(
    "https://raw.githubusercontent.com/disposable-email-domains/disposable-email-domains/main/disposable_email_blocklist.conf"
).text.split()

def is_disposable(email):
    domain = email.split("@")[1]
    return domain in DISPOSABLE_DOMAINS

Option 2: Use a Ready-Made API (Faster Setup)

Or skip all that complexity and use a ready-made solution.

I built this to solve the problem: https://apify.com/mayno/email-risk-scorer

What you get out of the box:

✅ 500+ disposable domains detected (Mailinator, Guerrilla Mail, YOPmail, etc.)
✅ MX record validation - checks if the domain can actually receive emails
✅ Email provider identification - detects Google Workspace, Microsoft 365, Zoho, etc.
✅ Free vs business email classification - Gmail/Yahoo vs company domains
✅ Role-based email detection - flags generic addresses (info@, admin@, noreply@)
✅ Automatic syntax validation - RFC-compliant email format checking
✅ Risk level scoring - returns low/medium/high based on multiple signals
✅ Batch processing - validate up to 10,000 emails per run
✅ No maintenance - disposable domain list updated automatically
✅ Fast processing - handles 1,000 emails in ~3-5 seconds

Setup time: 5 minutes. Here's the complete implementation for an Express.js signup route:

import { ApifyClient } from 'apify-client';

const apifyClient = new ApifyClient({ token: 'YOUR_APIFY_TOKEN' });

app.post('/signup', async (req, res) => {
  const { email, password } = req.body;

  // Check email risk (one API call)
  const run = await apifyClient.actor('mayno/email-risk-scorer').call({
    emails: [email]
  });

  const results = await apifyClient.dataset(run.defaultDatasetId).listItems();
  const emailRisk = results.items[0];

  // Block disposable emails
  if (emailRisk.isDisposable) {
    return res.status(400).json({
      error: 'Disposable email addresses are not allowed'
    });
  }

  // Block high-risk emails
  if (emailRisk.riskLevel === 'high') {
    return res.status(400).json({
      error: 'This email address cannot be used for registration'
    });
  }

  // Optional: Flag free email providers for review
  if (emailRisk.isFreeProvider && !emailRisk.hasMXRecord) {
    // Log for manual review
    console.log('Suspicious signup:', email);
  }

  // Proceed with signup
  await createUser(email, password);
  res.json({ success: true });
});

Example API response:

{
  "email": "test@mailinator.com",
  "isValid": true,
  "isDisposable": true,
  "isFreeProvider": false,
  "isBusinessEmail": false,
  "isRoleBasedEmail": false,
  "domain": "mailinator.com",
  "hasMXRecord": true,
  "mxProvider": "mail.mailinator.com",
  "riskLevel": "high",
  "reasons": ["Disposable/temporary email provider"]
}

Why this beats the DIY approach:

No code to maintain (I handle updates)
No DNS infrastructure to manage
No edge cases to debug
No weekly domain list updates
Works day one, scales to millions

Time saved: ~6 hours initial setup + 1-2 hours/month maintenance = ship faster, focus on your product

Conclusion

Pick what works for your stage:

Early/MVP: DIY approach
Scaling: Use an API

Try It Yourself

Want to test it out? The actor is live on Apify with a free tier: https://apify.com/mayno/email-risk-scorer

Questions? Feedback? Drop a comment below. I'm actively working on this and would love to hear what features would be most useful!

DEV Community: MAYNO