Email typo checker and "Did you mean?" for signup forms

How the checker decides

Each domain is compared with about 40 big mailbox domains (Gmail, Yahoo, Outlook, Hotmail, iCloud, Proton, GMX, Yandex and others) using an edit distance that counts two swapped letters as one slip. It is the same suggestFix() engine the Vetto script runs on signup forms, so what you see here is what your visitors would see. The rules are deliberately conservative:

• One slip for most providers, two for long names. gamil.com becomes gmail.com; protonmial.cm becomes protonmail.com.
• Short brands only get ending fixes. AOL, GMX, Live, Zoho and mail.ru are too close to real company names to guess at.
• Regional domains stay as they are. yahoo.se is real; gmail.co and gmail.cm are classic slips.
• Broken endings on any domain. .con, .cmo, .ocm, .nte or .ogr are fixed to .com, .net or .org, even on a company domain.
• A missing dot. jane@gmailcom becomes jane@gmail.com.

This page works offline, so it cannot tell whether a typo domain has a mail server of its own. For that, paste the address into the live disposable email checker, which looks up the domain's MX records.

The most common domain typos

Typos are not rare. In BounceZero's 2026 report on 7.8 million addresses run through its validation pipeline (vendor data from a mix of outreach, B2B, CRM and newsletter lists), gnail.com made up 0.31% of addresses, gmial.com 0.24% and gmai.com 0.18%, followed by gmal.com (0.12%) and hotmial.com (0.11%) (BounceZero, State of Email Validation 2026). Here is what the engine suggests for the usual suspects, computed live from the same code:

Typo domains that accept mail: gmai.com and friends

Some typo domains are dead and bounce. Others quietly accept your mail. When we looked up DNS on October 10, 2026, gmai.com and gnail.com both published MX records pointing at mail servers that are not Google's, while gmail.co published a null MX that refuses all mail. A welcome email or password reset sent to the first two does not bounce. It lands with whoever runs that server.

This is not a theoretical risk. Researchers at Carnegie Mellon registered 76 typo domains and received millions of emails in just over seven months. They projected that 1,211 typo domains registered by others receive around 800,000 emails a year, and found millions of typo domains whose MX records point to a handful of mail servers (Szurdi and Christin, Email Typosquatting, IMC 2017). In 2023, Keio University started blocking outgoing mail from its own system to Gmail lookalikes such as gmai.com and gmail.co, after misdirected mail led to information leaks (Keio ITC, 2023).

Suggest, don't auto-correct

It is tempting to rewrite .con to .com silently. Don't. In a Marketo community thread on correcting email typos, a veteran contributor pointed out that .con could have been meant as .com or .cn, and that even smarter systems are never fully accurate (Adobe Marketo community). Vetto suggests .com because it is by far the likelier intent, but the visitor decides.

Real domains also sit one letter away from a big provider, and rewriting them sends a real customer's mail somewhere else. Here is what the engine does with a few of them (again computed from the code):

So the rule is simple: show "Did you mean jane@gmail.com?" with a Fix button, apply it on one click, and let a second submit go through unchanged.

Add one-click typo rescue to your form

Paste one line before the closing body tag of any page with a signup form:

<script src="https://usevetto.com/v.js" data-site="pk_your_public_key" defer></script>

When a visitor leaves the email field, the script checks the address. A typo gets a "Did you mean …? [Fix]" line under the field, and the dashboard ledger counts every signup rescued by that click. The same check blocks throwaway inboxes and dead domains, lets privacy relays such as Apple Hide My Email through, and fails open: if Vetto does not answer within 800 ms, the form submits as if it were not installed. Typo rescue is on the Free plan: 1 site, 1,000 checks a month, no card. See pricing for Pro.

Already have users with broken addresses? Run the free CSV email list audit to find typos, throwaways and dead domains in your existing list. Only domain names leave your browser.

Mailcheck.js or a hosted check?

Mailcheck is the classic library for this job. It is MIT-licensed, has no runtime dependencies and makes no network requests, and its README is clear that it is a typo suggester, not an email validator or a deliverability check (mailcheck on GitHub). If you can't load a third-party script, or you only want suggestions, it is a fine choice.

A hosted check earns its place when you also want to stop what a typo list cannot see: throwaway inboxes, dead domains, lookalikes with a live mail server and Gmail alias farms (the last two on Pro, which also signs each verdict for your backend). The Mailcheck.js alternative comparison goes through the trade-offs, and the guide to blocking disposable emails on any signup form covers server-side enforcement.