Is that a temporary
email address?
Paste an address or a domain to see whether it comes from a throwaway mailbox provider — before it lands in your database and starts bouncing.
Free · no account · addresses are discarded
//Sender reputation\\
Why throwaway signups cost you
A burner address is not just a junk row in your database. It actively degrades the deliverability of every other message you send.
Throwaway inboxes expire. Most temporary mailboxes are destroyed within an hour. Every send after that is a hard bounce recorded against your domain.
Mailbox providers keep score. Sustained bounce rates push your domain toward the spam folder for every recipient, not just the disposable ones.
Your metrics stop lying. Burner signups inflate list size and deflate open rates. Filtering them keeps growth numbers honest.
Free tiers get farmed. Unlimited throwaway addresses mean unlimited trial accounts. Blocking them at signup closes the cheapest abuse vector you have.
//Nothing hidden\\
What the check looks at
A verdict is only useful if you can see how it was reached. Every signal behind the result is reported on its own.
Address syntax. The local part and domain are parsed against RFC 5322 shape rules, so malformed input is rejected before anything else runs.
Disposable domains. The domain is matched against a large, continuously refreshed catalogue of known throwaway mailbox providers.
Wildcard patterns. Providers spin up endless subdomains. Suffix patterns catch the whole family instead of one host at a time.
Exception list. Legitimate domains that share infrastructure with throwaway services stay whitelisted, so real customers are never blocked.
Role addresses. Shared inboxes like info@, billing@ and support@ are flagged separately — they are real, but they behave differently.
Free providers. Consumer mailboxes are called out on their own, so you can treat them differently from throwaway addresses.
//Developer first\\
Run the same check from your code
This page is a thin wrapper over one public endpoint. Point your signup flow at it and reject burner addresses before the account is created.
POSThttps://reloop.sh/api/tool/v1/check
curl -X POST https://reloop.sh/api/tool/v1/check \
-H "Content-Type: application/json" \
-d '{"email": "you@mailinator.com"}'{
"input": "you@mailinator.com",
"kind": "email",
"domain": "mailinator.com",
"verdict": "disposable",
"isValidSyntax": true,
"isDisposable": true,
"disposableMatch": {
"kind": "exact",
"domain": "mailinator.com"
},
"isAllowlisted": false,
"isRoleAddress": false,
"isFreeProvider": false,
"signals": {
"syntax": "pass",
"disposable": "fail",
"role": "pass",
"freeProvider": "pass"
}
}No key, no account. The endpoint is public and unauthenticated. It is rate limited per IP, so keep it to signup-time checks rather than bulk list scrubbing.
Nothing to wait on. Matching runs in memory against the loaded domain catalogue — no DNS lookup, no SMTP probe, no third-party call behind the scenes.
Frequently asked questions
Basics
A disposable — or temporary, throwaway, burner — email address is a mailbox created on demand that anyone can read without signing up, and that usually self-destructs within minutes or hours. People use them to get past signup walls without handing over a real address.
Because they stop existing. Once the mailbox expires, every message you send to it hard-bounces, and mailbox providers read sustained bounce rates as a sign that you send to bad lists. That reputation damage applies to your whole domain, not just the throwaway recipients.
Not necessarily. Blocking outright at signup is right for free tiers and trials, where throwaway addresses are used to farm accounts. For newsletters or content downloads, flagging and suppressing later is often enough — some people simply value their privacy.
Accuracy
Domain matching is exact by nature: a domain is either on the list or it isn't. The lists themselves are community maintained and refreshed continuously, but new providers appear constantly, so treat a clean result as 'not currently known to be disposable' rather than a guarantee.
No. Consumer mailboxes from Gmail, Outlook, Yahoo and similar providers are free, but they are persistent and real. They are reported as a separate signal so you can apply your own policy to them — many products happily accept them.
Privacy & API
No. Addresses are checked and discarded — nothing is written to a database, added to a list, or used for marketing. The tool is free and needs no account.
Yes. Reloop is open-source email infrastructure, so you can run the same validation inside your own signup flow, self-host the whole stack, or use the hosted API. Nothing here is locked behind a proprietary service.
Stop sending to inboxes
that no longer exist.
Reloop is open-source email infrastructure — validation, sending, inbound, and analytics in one stack you can host yourself.