How to use Emailable API to validate emails in real time for web forms

If you've ever had a signup form flooded with fake or typo-ridden email addresses, you know the pain of bad data. Real-time email validation can save you a lot of headaches and wasted effort, but most solutions either miss obvious fakes or slow down your form. This guide is for developers or anyone building a website who wants a practical, no-nonsense way to check if an email is real, using the Emailable API.

Here’s what you’ll actually learn: How to set up Emailable’s API, wire it up to a web form, show instant feedback to users, and avoid the common mistakes that make validation annoying or unreliable.

1. Why Bother With Real-Time Email Validation?

Let’s be real: every website that collects emails gets junk. Bots, typos, throwaway accounts—if your system doesn’t catch these, you’re wasting time and money. Real-time validation checks the email as users type, so you can:

  • Catch typos instantly (e.g., gmal.com instead of gmail.com)
  • Block obvious fakes (like test@test.com)
  • Reduce bounce rates for newsletters and signups
  • Cut down on manual cleanup later

But, if you make validation too strict or slow, you’ll annoy real users. The trick is to strike the right balance.

2. What the Emailable API Actually Does (and What It Doesn’t)

The Emailable API checks if an email address looks valid, is properly formatted, and—optionally—whether the address exists on the mail server. It gives you a confidence score and some flags (e.g., “disposable,” “role-based,” “free provider”).

What works well: - Catches most typos and fake domains - Flags disposable email addresses - API is well-documented and fast (usually < 1 second)

What doesn’t: - No API can guarantee a 100% deliverable address—people can give you a working but ignored email - Some privacy-focused or weird mail servers block verification - Too-aggressive blocking (like banning all “free” emails) will frustrate legit users

Bottom line: Use this as a guide, not gospel. Don’t auto-block everyone the API says is “risky”—use it to nudge users or flag for review.

3. Step-by-Step: Hooking Up Emailable API to Your Web Form

Let’s break it down. You’ll need:

  • An Emailable account (free tier is usually fine to start)
  • A web form (plain HTML, React, Vue, whatever)
  • Basic JavaScript skills

Step 1: Get Your Emailable API Key

  1. Sign up at Emailable.
  2. Go to your dashboard.
  3. Find your API key (usually under “API” or “Integrations”).

Pro tip: Never put your secret API key in client-side JavaScript. For client-side validation, use their “public” API endpoint, or proxy requests through your server.

Step 2: Decide When to Validate

You’ve got two main options:

  • On blur: Validate after the user leaves the email field.
  • On submit: Validate right before the form submits.

On blur is more user-friendly—people get feedback as they type, but you’ll use more API calls (so watch out if you pay per request). On submit is cheaper, but users might only see errors after filling out the whole form.

For most sites, validate on blur, but throttle requests so you don’t hammer the API on every keystroke.

Step 3: Make the API Request

Here’s a basic example using JavaScript (with fetch). This version runs when the user leaves the email field.

html

javascript document.getElementById('email').addEventListener('blur', async function() { const email = this.value.trim(); if (!email) return;

document.getElementById('email-feedback').textContent = 'Checking…';

try { const response = await fetch('https://api.emailable.com/v1/verify?email=' + encodeURIComponent(email) + '&api_key=YOUR_PUBLIC_API_KEY'); if (!response.ok) throw new Error('API error'); const result = await response.json();

// Check the result and show a message
if (result.state === 'deliverable') {
  document.getElementById('email-feedback').textContent = 'Looks good!';
  document.getElementById('email-feedback').style.color = 'green';
} else if (result.state === 'undeliverable') {
  document.getElementById('email-feedback').textContent = 'This email can’t be delivered. Check for typos.';
  document.getElementById('email-feedback').style.color = 'red';
} else if (result.state === 'risky') {
  document.getElementById('email-feedback').textContent = 'This email looks risky or disposable.';
  document.getElementById('email-feedback').style.color = 'orange';
} else {
  document.getElementById('email-feedback').textContent = 'Couldn’t validate this email.';
  document.getElementById('email-feedback').style.color = 'gray';
}

} catch (err) { document.getElementById('email-feedback').textContent = 'Error validating email.'; document.getElementById('email-feedback').style.color = 'gray'; } });

Don’t forget: Replace YOUR_PUBLIC_API_KEY with your actual key. If you’re worried about someone abusing your API key, set up a simple backend (Node, Python, etc.), and proxy the request through there.

Step 4: Show User-Friendly Errors (Not Just “Invalid Email”)

Most users don’t know (or care) what “undeliverable” means. Be specific, and always offer a way forward. For example:

  • “Looks good!” (green checkmark)
  • “This email can’t be delivered. Check for typos.” (helpful, not accusatory)
  • “This email looks risky or disposable.” (orange, but still lets them continue if they want)

Don’t:
- Block users from proceeding unless you’re 100% sure the email is fake. - Show cryptic API error messages.

Step 5: Handle Edge Cases and Rate Limits

A few things to watch for:

  • API limits: Free plans have a monthly limit. If you go over, the API will stop working or throttle you.
  • Network errors: If the API fails, don’t block the user—just let them proceed and maybe re-validate later.
  • False positives: Some legit emails will come up as “risky” or “unknown.” Don’t punish users for this.

Quick workaround: If the API returns “risky” or errors out, let the user continue, but maybe flag the account for manual review.

Step 6: Go Beyond Basic Validation (Optional)

If you want to get fancy, Emailable's API returns more than just "valid/invalid." You can check:

  • If the address is disposable (temporary inboxes)
  • If it’s role-based (e.g., admin@, info@)
  • If it’s a free provider (like Gmail or Yahoo)

You can use these flags to:

  • Warn users about using disposable emails
  • Block signups from role accounts (e.g., if you only want personal addresses)
  • Collect analytics on the types of emails your users use

Just don’t go overboard. Lots of legit people use Gmail, and sometimes teams sign up with info@—so don’t block them unless you have a really good reason.

4. Example: Full HTML + JS Form

Here’s a barebones example you can actually use:

html

Swap out YOUR_PUBLIC_API_KEY for your real key. This version only blocks obviously undeliverable emails; everything else gets a warning or passes through.

5. What to Skip (and What Not to Overthink)

  • Don’t block users for using Gmail, Yahoo, or other free providers. You’ll lose legit signups.
  • Don’t block all “risky” or “unknown” emails. You’ll get false positives, and it’s not worth the support tickets.
  • Don’t rely on the API alone. Even with validation, some bad emails will sneak through.
  • Don’t show users the raw API response. It’s not always clear or friendly.

If you want to get fancy, you can debounce the API calls (so you don’t call the API on every keystroke), or pre-check the email pattern with a simple regex before hitting the API.

6. Wrapping Up: Keep It Simple, Iterate Later

Real-time email validation is one of those things that’s easy to overcomplicate. Start simple: check emails on blur, show clear feedback, and only block the truly undeliverable stuff. Watch how users respond and adjust your rules over time.

Don’t stress about catching every edge case on day one. The goal is to cut down on obvious junk, not to create a signup process so airtight that real users give up. Keep it practical, and tweak as you go.