Free tool — no signup
Free email validator
Paste an address. You get the checks that cost nothing to run — syntax, a live MX lookup, disposable and role detection — plus an honest list of the ones we didn't run, because guessing deliverability we never tested would be lying.
Try a real domain vs a throwaway — or .
SampleA real response for this input — press Verify to run it live.
Checked
Not claimed — we won't fake it
What the free check covers
Everything it checks — and everything it won't fake.
Checked
Runs on every result above.
RFC-shaped local and domain parts, total length within 254 characters — the thing a regex reaches for, done properly.
A live DNS lookup (over DoH) for the domain's mail servers. No MX means no mailbox can receive mail there, whatever the syntax says.
The domain checked against a maintained list of throwaway-inbox providers — Mailinator, Guerrilla Mail, 10-minute-mail and the rest.
Whether it's a shared alias — info@, support@, admin@ — rather than a real person's mailbox.
Whether it's a consumer mailbox (Gmail, Outlook, Yahoo) or a corporate domain — context, not a verdict.
Not claimed
Marked not-run in the result, never guessed.
We don't open an SMTP conversation to ask whether the exact mailbox exists. It's slow, rate-limited, and a large share of servers answer "yes" to everything — so a positive would mean nothing. Marked not-run, never guessed.
Whether the domain silently accepts every address (which makes any single-mailbox check meaningless). Reported as not tested.
Validation and verification aren't the same word
Three layers, and vendors blur them. This tool runs the first two and marks the third not-run.
- Syntactic validationIs the string shaped like an address? runs here
- Domain verificationCan the domain receive mail at all? — the live MX lookup runs here
- Mailbox verificationDoes that specific inbox exist? — needs an SMTP probe not run
Anyone claiming to "verify" every mailbox in bulk, instantly, at zero cost is selling you a guess wearing a checkmark.
Why a regex isn't enough
A regex proves an address is shaped right. It cannot tell you whether the domain can receive mail.
Regex alone
test@nonexistent-domain-9f2.com
valid_syntax: true
Passes almost every regex ever written.
This tool
test@nonexistent-domain-9f2.com
mx_found: false
No mail servers. The check that lives past the regex.
Both verdicts are real fields from this page's own API, captured 9 August 2026 — paste the address above to re-run it.
What "disposable" and "role" are actually for
Two flags that matter most at the signup form. Both are inputs to your policy, not automatic rejections.
Disposable
x9f2q@mailinator.com
Throwaway inbox: fraud usage, bounce damage to your sender reputation, analytics noise.
Role account
support@acme.com
Legitimate address, poor fit for a personal onboarding sequence.
Your call, our disclosure.
Questions
Is this email validator really free?
Yes — no signup, no card. It runs the same zero-cost checks the API's free tier runs. There's an hourly per-visitor limit to keep it from being abused; past that, the free API tier gives you 250 checks a month, still no card, and the credits never expire.
Does it check whether the mailbox actually exists?
No, and it says so on every result. Mailbox-level existence needs an SMTP probe, which is slow and unreliable — many mail servers accept-then-bounce or answer positively to everything. Rather than dress a guess up as a verdict, we mark SMTP mailbox and catch-all as not-run.
What's the difference between email validation and verification?
Validation usually means the format is correct. Verification usually means the address can actually receive mail. This tool validates syntax, verifies the domain has mail servers (MX), and flags disposable, role and free-provider addresses — and is explicit that it does not verify the individual mailbox.
Can I validate a whole list of emails at once?
Yes, through the API's bulk endpoint — upload a CSV and get one back with a verdict per row, credits reserved per row and refunded for any that error. The free interactive tool above is one-at-a-time by design.
How do I validate emails in my own code?
One POST to /v1/verify/email with a bearer key. The response carries the same fields you see here, including checks.performed and checks.not_performed so your code can tell what a verdict was actually based on. Full reference at boundstone.io/docs.
Need this in your signup flow, or across a whole list?
The same checks, one HTTP call — with checks.performed / not_performed on every response, so your code knows what a verdict was based on.
curl -X POST https://api.boundstone.io/v1/verify/email \
-H "authorization: Bearer bs_live_YOUR_KEY" \
-H "content-type: application/json" \
-d '{"email":"you@example.com"}'
# → { valid_syntax, mx_found, disposable, role_account,
# free_provider, checks: { performed, not_performed } }
Early access — free tier is 250 credits/month, forever
The API is live — start free without waiting. This list gets benchmark № 001 the day it publishes. One email. We validate emails for a living — we're not going to spam yours.