Email Checker
Screen any email address to decide whether it's disposable or temporary — a throwaway inbox like mailinator or 10minutemail — combining a daily-refreshed blocklist with a mail-server fingerprint, before you trust a signup or a report.
Why It Matters
Throwaway inboxes — mailinator, 10minutemail, guerrillamail, temp-mail — let anyone sign up, submit a report, or claim a bounty without a real, reachable address. When you need to decide whether an address is worth trusting, guessing from the domain name doesn’t scale: new disposable providers appear constantly, and some hide behind fresh front-domains. The Email Checker gives a responder a one-glance verdict from a single lookup.
What It Does
Paste one email address — or a whole list, one per line — and each gets a verdict:
- Disposable — the address belongs to a known throwaway provider.
- Looks legitimate — nothing flags it as disposable.
- Invalid — the address isn’t a structurally valid email at all.
Each result also shows why (known disposable domain, disposable mail server, or a formatting problem), the domain, and whether the domain has mail servers.
How the verdict is reached
| Signal | What it checks |
|---|---|
| Format | Structural validity of the address (regex) |
| Blocklist | Whether the domain is on a curated, daily-refreshed list of disposable-email providers |
| Mail-server fingerprint | Whether the domain’s MX servers belong to a known disposable provider — catching brand-new front-domains the blocklist hasn’t listed yet |
Note
“Looks legitimate” means nothing flagged the address as disposable — not that the inbox has been proven to exist or that mail will be delivered. Absence of a disposable signal isn’t a delivery guarantee.
Tip
Turn off Check mail servers for an instant, blocklist-only answer with no DNS lookup. Leave it on to also catch fresh throwaway domains whose mail servers give them away.
Screening an Email
Open the Email Checker page. Any signed-in account member can use it.
- Paste one address, or a list separated by new lines, spaces, or commas.
- Choose whether to check mail servers (on by default).
- Submit — a verdict card renders inline for each address.
Where the Data Comes From
The disposable-domain blocklist is the curated, low-false-positive disposable-email-domains list, refreshed daily into Kit. It deliberately excludes privacy relays and large regional providers (Apple Hide My Email, DuckDuckGo/Firefox Relay, and the like) so real, permanent addresses aren’t mistaken for throwaways. The mail-server fingerprint uses public DNS. The tool never touches or exposes your account data, and nothing you screen is persisted.
Limits
| Limit | Value |
|---|---|
| Batch size | Up to 25 addresses per screening; the rest are noted and can be screened separately |
| Mail-server check | A DNS lookup per address, bounded by a short timeout — an unreachable resolver reports mail servers as “not checked” rather than hanging |
| Coverage | The blocklist catches the vast majority of disposable providers; the mail-server fingerprint extends it to fresh front-domains, but a brand-new provider with its own infrastructure can still slip through until the list catches up |
Quick Checklist
- Open the Email Checker page
- Paste one address, or up to 25 at once
- Leave Check mail servers on to catch fresh throwaway domains
- Treat a “disposable” verdict as a reason to require a real address before you trust the signup or report