Disposable email detection API

What is disposable-email detection?

A disposable email address is one created specifically to be used once and then abandoned. Services like Mailinator, 10 Minute Mail, Guerrilla Mail, and hundreds of rotating lookalikes let anyone generate a working inbox in seconds, with no verification and no cost. People use them to skip email confirmation, claim a “new signup” free trial or discount more than once, or join a mailing list without ever intending to read it.

Disposable-email detection means checking whether an email address belongs to one of these throwaway services before you create the account, add the subscriber, or spend a free-trial credit. As a disposable email detection API, Mailsurity does this by checking the domain against a constantly growing list of known throwaway providers, then falling back to live analysis for domains nobody has cataloged yet.

Types of disposable-email services

“Disposable email” covers a few different setups, and a detector that only handles the first one misses the rest:

A name-only blocklist catches the first type and struggles with the other two, since the domain name itself is disposable. Mailsurity's disposable email detection API is built to catch all three: layer five of the cascade below checks the reputation of the mail server actually receiving a domain's email, not just the domain name, which is exactly what the second and third cases need.

Why disposable signups hurt deliverability

A disposable signup rarely stays neutral. The confirmation or welcome email either hard-bounces once the throwaway inbox expires, or lands in an inbox nobody ever intended to keep. An address that was never going to engage is far more likely to get marked as spam than politely unsubscribed.

Bounce and complaint rates feed directly into how mailbox providers (Gmail, Outlook, and the rest) score your sending domain. A list full of disposable addresses drags that score down for everyone on it, including the real subscribers and customers you actually want landing in the inbox, not the spam folder. Catching disposable addresses at signup protects deliverability for every email you send afterward, not just the one that got blocked.

Who this is for

Why static blocklists miss new domains

Throwaway-mail providers spin up new domains constantly, on purpose: it's how they dodge blocklists. A .json file of bad domains downloaded from a public repo is out of date by the time you deploy it. Mailsurity runs every check through five layers, in order, so a static list is only ever one of them:

That's the gap a static list can't close: a brand-new throwaway domain gets caught the first time it ever shows up, not weeks later after someone notices it and adds it to a list.

Layer 5, live detection, is what actually closes that gap. Instead of checking the domain name against a list, it resolves the domain's mail servers and scores it on the spot: how random or high-entropy the name itself looks, how closely it resembles known throwaway-service naming patterns, and the reputation of the mail servers behind it. Only a genuinely unclear result escalates to an AI model. That means a burner domain can get flagged on the very first request it ever makes, before anyone has manually added its domain name anywhere.

This is exactly where the bulk-registered lookalike clusters described above show up in practice: dozens of near-identical burner domains sharing a handful of mail servers. Once one of those mail servers has been seen serving throwaway addresses, Mailsurity remembers it, so the next brand-new sibling domain pointed at the same server inherits that suspicion immediately, rather than needing its own name individually catalogued first.

Calling the disposable email detection API

One HTTP call, JSON in and out, no SDK to install. Send the email, read isDisposable off the response:

curl -X POST https://www.mailsurity.com/api/check-email \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "email": "user@mailinator.com" }'

A throwaway address comes back like this:

{
  "email": "user@mailinator.com",
  "isDisposable": true,
  "source": "list"
}

Full authentication details, error codes, and copy-paste examples in eight languages are in the API reference.

How Mailsurity compares

Kickbox and ZeroBounce are full-stack email-verification platforms; disposable detection is one flag among many they check. BounceZero is a closer competitor: a dedicated disposable-email checker that claims 99.8% accuracy and 65+ signals on its own site. DeBounce is closer on price: it runs a free disposable-check API, no signup mentioned. Disposable, temporary, and fake email detection is Mailsurity's only product, not one flag among many.

Mailsurity pricing shown is live from our current plans. Competitor figures are sourced from each vendor's public pricing page, last verified 2026-07-25 — confirm current rates before deciding. See the full comparisons hub for more vendor breakdowns.

Go deeper: integration guides

Step-by-step walkthroughs for wiring disposable-email checks into the stack you already run — or see the full guides index.

Evaluating this for a security or compliance review? See the Trust & Security page for subprocessors, certifications, and data-retention details.

Frequently asked questions