AI Prompt

Add disposable email validation to my app using the @isdisposable/js package.

## What to do:
1. Install the package: npm install @isdisposable/js
2. Find where users sign up or submit their email (signup forms, registration, invite flows, waitlist, etc.)
3. Before creating the user or processing the email, add a check
4. If the email is disposable, reject it with a clear error message like "Please use a permanent email address"

## Option A — Offline check (simple, instant):
- import { isDisposable } from '@isdisposable/js'
- isDisposable('test@mailinator.com') returns true (disposable)
- isDisposable('user@gmail.com') returns false (legitimate)
- It's synchronous, returns a boolean, zero dependencies, works offline
- 160,000+ known disposable domains bundled in the package
- For bulk checking: import { isDisposableBulk } from '@isdisposable/js'

## Option B — API check (real-time, catches new domains):
- import { createIsDisposable } from '@isdisposable/js'
- const client = createIsDisposable({ apiKey: 'isd_your_key' })
- const { disposable, score, reason } = await client.check(email)
- Returns a score (0-100), reason, and disposable boolean
- Built-in caching, configurable timeout, automatic offline fallback
- For bulk: await client.checkBulk(['email1@test.com', 'email2@test.com'])
- Get an API key at https://isdisposable.com/dashboard/api-keys

## Rules:
- Check BEFORE creating the user in the database, not after
- Show a user-friendly error, not a generic 400
- Don't log the full email for privacy — only log the domain if needed
- The offline check is instant (<1ms), the API check takes 1-5 seconds
- Make sure to check on the server side, not client side (client checks can be bypassed)

Add disposable email blocking to my Next.js app using @isdisposable/js.

Install: npm install @isdisposable/js

Add this check in my signup server action or API route:

import { isDisposable } from '@isdisposable/js';

if (isDisposable(email)) {
  return { error: 'Please use a permanent email address. Disposable emails are not allowed.' };
}

Find all places where users submit emails (signup, invite, waitlist, contact forms) and add this check before processing. The function is synchronous and returns a boolean. It works on the server side, edge runtime, and middleware.

Add disposable email blocking to my Express app using @isdisposable/js.

Install: npm install @isdisposable/js

Add this middleware or inline check on any route that accepts emails:

import { isDisposable } from '@isdisposable/js';

// In your signup/registration route:
if (isDisposable(req.body.email)) {
  return res.status(400).json({ error: 'Please use a permanent email address.' });
}

Find all routes where users submit emails and add this check before creating the user. The function is synchronous, returns a boolean, and has zero dependencies.

Add disposable email blocking to my Better Auth setup using @isdisposable/js.

Install: npm install @isdisposable/js

Add this to my auth config using databaseHooks:

import { isDisposable } from '@isdisposable/js';

export const auth = betterAuth({
  // ... existing config
  databaseHooks: {
    user: {
      create: {
        before: async (user) => {
          if (isDisposable(user.email)) {
            throw new APIError('BAD_REQUEST', {
              message: 'Please use a permanent email address. Disposable emails are not allowed.',
            });
          }
          return user;
        },
      },
    },
  },
});

Import APIError from 'better-auth/api'. This blocks disposable emails before the user is created in the database.

Add disposable email blocking to my Supabase app using @isdisposable/js.

Install: npm install @isdisposable/js

Before calling supabase.auth.signUp(), check the email:

import { isDisposable } from '@isdisposable/js';

// In your signup handler (server-side):
if (isDisposable(email)) {
  return { error: 'Please use a permanent email address.' };
}

// Only proceed with signup if email is clean:
const { data, error } = await supabase.auth.signUp({ email, password });

Add this check on the server side (API route or server action), not on the client.

Add real-time disposable email detection to my app using the @isdisposable/js API client.

Install: npm install @isdisposable/js

Create a client instance (do this once, e.g., in a lib/email.ts file):

import { createIsDisposable } from '@isdisposable/js';

export const emailChecker = createIsDisposable({
  apiKey: process.env.ISDISPOSABLE_API_KEY!,
  // timeout: 5000,  // optional, default 5s
  // cache: true,     // optional, default true
  // cacheTTL: 3600,  // optional, default 1 hour
});

Use it in signup/registration handlers:

const { disposable, score, reason } = await emailChecker.check(email);
if (disposable) {
  return { error: 'Please use a permanent email address.' };
}

The client automatically:
- Calls the isDisposable API for real-time DNS/MX analysis
- Caches results to avoid repeat API calls
- Falls back to offline blocklist if the API is unreachable
- Supports bulk checking: await emailChecker.checkBulk(emails)

Get an API key at https://isdisposable.com/dashboard/api-keys

## Email Validation

Always validate emails against disposable/temporary email providers before creating users or processing signups.

Use the @isdisposable/js package:
- import { isDisposable } from '@isdisposable/js'
- isDisposable(email) returns true if the email is disposable
- Check on the server side, before database writes
- Show a clear error: "Please use a permanent email address"