canonical: https://jentic.com/apis/mailboxvalidator.com

# MailboxValidator APIs

MailboxValidator provides email intelligence APIs that verify and enrich individual email addresses. Its endpoints run syntax, MX, and SMTP checks, flag free-webmail and disposable providers, detect role-based aliases, and return a numeric deliverability score, all keyed off a single email address per call. The three APIs share one host and one credit-based API key, so teams can pick a lightweight single-signal check or the full validation product depending on how much detail a workflow needs.

## For AI agents

An agent can take one email address and, across these APIs, decide whether it is a free-webmail address, a disposable throwaway inbox, or a fully deliverable mailbox with MX and SMTP confirmed and a numeric score. That lets the agent gate signups, qualify B2B leads, and clean mailing lists before a send.

## Scope

Use for: Verifying and classifying individual email addresses (free-provider, disposable, syntax, MX, SMTP, role, and deliverability score) one address per call

Not supported:
- bulk validation
- sending email
- suppression list management
- real-time streaming

## APIs

| API | Category | Endpoints | Description |
| --- | --- | --- | --- |
| MailboxValidator Disposable Email Checker | data-enrichment | 1 | Detect disposable, throwaway, or temporary email addresses on a single GET - block trial abuse and signup spam at the form layer. |
| MailboxValidator Email Validation | data-enrichment | 1 | Validate one email address and return the full MailboxValidator signal set - syntax, MX, SMTP, free, disposable, role, and score - in a single GET. |
| MailboxValidator Free Email Checker | data-enrichment | 1 | Check whether a single email address belongs to a free webmail provider - useful for filtering personal addresses out of B2B lead routing. |

## Which API to use

| Need | API | Why |
| --- | --- | --- |
| Filter personal addresses out of B2B lead routing | checker | Returns only the free-webmail verdict, the cheapest signal for separating consumer from corporate addresses. |
| Block trial abuse and signup spam | disposable | Flags throwaway inboxes such as 10minutemail and mailinator without spending credits on full validation. |
| Confirm an address is genuinely deliverable before sending | validation | Runs syntax, MX, and SMTP checks and returns a numeric score plus free, disposable, and role flags in one call. |

## Cross-API use cases

### Two-stage signup gate

An agent screens a new signup by first checking whether the address is disposable and whether it is a free-webmail domain, then only escalates borderline cases to a full validation. This spends the fewest credits on obvious rejects while still confirming deliverability for the addresses worth keeping.

Example prompt: On each new signup, call the disposable check and the free-provider check; reject disposable addresses, tag free-webmail addresses for review, and pass the rest through.

### Lead qualification with deliverability confirmation

An agent qualifies inbound B2B leads by flagging free-webmail addresses to deprioritize consumer signups, then running the full validation to confirm MX, SMTP, and a deliverability score before routing a lead to a sales rep. Corporate, deliverable leads reach an AE while free-mail or undeliverable ones go to a nurture track.

Example prompt: For each inbound lead, run the free-provider check, then the full validation; route the lead to sales only when it is a business domain with a score of at least 0.7.

### Mailing list hygiene pass

An agent cleans an existing subscriber list by removing disposable addresses and validating the remainder for MX and SMTP so bounce-driven reputation damage is reduced before the next campaign. Disposable and undeliverable addresses are suppressed while deliverable ones are retained.

Example prompt: For each subscriber, call the disposable check, suppress throwaway addresses, then run full validation and suppress any remaining address whose score falls below the send threshold.

## Why Jentic

- **Setup:** Instead of wiring each MailboxValidator endpoint to the api.mailboxvalidator.com host and threading your key through every request, you install Jentic One once and your agent adds the free-provider, disposable, and validation operations from the Jentic directory. One install covers all three APIs.
- **Permission scoping:** Each MailboxValidator API is a single read-only lookup, so you can scope your agent to just the checks a workflow needs, for example the disposable and free-provider endpoints for signup screening while leaving full validation out. Your own rules decide which operations are in scope.
- **Credential handling:** Your one MailboxValidator API key is stored encrypted by your own Jentic One instance and injected at execution time across all three APIs. It never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search the Jentic directory by intent such as 'is this a disposable email address' or 'fully validate an email', and Jentic returns the matching MailboxValidator operation with its input schema so the agent picks the right endpoint without reading the reference docs.

## Related vendors

- **mailboxlayer** — Real-time email validation that returns free-provider, disposable, MX, and a deliverability score together in one call.
- **ZeroBounce** — Email validation with AI-scored deliverability and abuse detection plus email service provider integrations.
- **Kickbox** — Email verification that bundles a disposable flag with a confidence-graded deliverability verdict and SMTP check.

## FAQ

### What can I do across the MailboxValidator APIs?

You can classify a single email address as free-webmail or business, detect disposable throwaway inboxes, and run a full validation that returns syntax, MX, SMTP, free, disposable, and role signals plus a numeric deliverability score. Each API works on one address per call.

### Do all three APIs share one API key?

Yes. The free-provider checker, the disposable checker, and the full validation endpoint all use the same MailboxValidator API key, and every call draws on one shared credit-based subscription.

### Which API should I use for a given task?

Use the free email checker when you only need to separate consumer addresses from business ones, the disposable checker to block throwaway inboxes at signup, and the full validation endpoint when you need MX, SMTP, and a deliverability score in one call. The single-signal endpoints spend fewer credits than full validation.

### How are credits consumed across the endpoints?

MailboxValidator uses a credit model rather than a per-second rate limit, and every call against any of the three endpoints draws credits from the same monthly allowance. Choosing a lightweight single-signal check conserves credits compared with running full validation on every address.

### Can I combine these APIs in one workflow?

Yes. A common pattern runs a cheap disposable or free-provider check first and only escalates borderline addresses to full validation, so an agent spends the least credits needed to reach a decision at signup, lead routing, or list cleaning.

### Do these APIs return JSON or XML?

All three endpoints accept a format query parameter that selects JSON or XML output, with JSON as the default and the recommended choice for agent and SDK consumers.

### Do the MailboxValidator APIs send email or process addresses in bulk?

No. Each endpoint verifies or classifies one address per call and does not send mail, manage suppression lists, or run bulk validation. They produce the signals your own send or routing logic acts on.