mailboxlayer
mailboxlayer is an apilayer-owned REST JSON API for email address verification. It performs syntax and typo checks, MX-record lookup, real-time SMTP verification, catch-all detection, role-address detection, free and disposable provider detection, and returns a numeric deliverability quality score. Useful for signup-form validation, list hygiene, lead enrichment, and fraud prevention.
Solid contracts, transparent operations, and an easy start — typically complete on four or five facets with one clear soft spot.
API Evangelist profiles mailboxlayer the way a machine reads it — 49 machine-readable artifacts across 1 API, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — mailboxlayer scores 63.2/100 (strong), with a separate agent-readiness read of 48/100 (agent ready). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile mailboxlayer
Each block below is one kind of artifact we hold for mailboxlayer. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 1
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
mailboxlayer Verification API
Email address validation and verification operations.
Open Collections 1
Open, tool-agnostic collections carry the same runnable value as Postman without locking you to one client — the portable, forkable form of the same exercise.
Open, tool-agnostic API collections (OpenAPI-derived and Bruno).
mailboxlayer API
OPEN COLLECTIONPricing Plans 1
Pricing is part of the interface. Machine-readable plans tell you what a tier costs and includes before you commit — one of the six things the Kin Score reads for commercial clarity.
Published pricing tiers and plan structures.
Rate Limits 1
Rate limits are the difference between a demo that works and a production integration that doesn't fall over. Publishing them is an operational-transparency signal — and a hard requirement for any agent that plans its own throughput.
Documented rate limits and quota policies.
Mailboxlayer Rate Limits
RATE LIMITSFinOps 1
Cost, billing, and metering signals let a buyer model the financial operations of an API before it's live. We profile them for the same reason we profile pricing: the money is part of the contract.
Cost, billing, and metering signals for API financial operations.
Mailboxlayer Finops
FINOPSFeatures 11
The notable capabilities this provider advertises, captured as structured features so they can be searched and compared instead of read one landing page at a time.
Notable capabilities this provider offers.
Syntax And Typo Check
Thorough RFC 5322 syntax validation with did-you-mean suggestions for likely typos.
Real-Time SMTP Verification
Each address is pinged via SMTP to confirm the mailbox actually accepts mail.
MX Record Lookup
Verifies that the email domain has functioning MX records.
Catch-All Detection
Determines whether the recipient domain accepts mail for any local part (paid plans only).
Role Address Detection
Flags addresses associated with a function rather than a person (support@, admin@, etc.).
Free Provider Detection
Identifies addresses on free webmail providers (Gmail, Yahoo, Outlook.com, etc.).
Disposable Provider Detection
Identifies addresses on throwaway / disposable providers (mailinator.com, etc.).
Quality Score
A 0.0 to 1.0 numeric score expressing overall deliverability and quality.
HTTPS Encryption
256-bit HTTPS transport on paid plans (Basic and above).
Bulk Endpoint
Submit 25 addresses (Pro Plus) or 100 addresses (Enterprise Plus) in a single request.
JSONP Support
JSONP wrapper via the `callback` query parameter.
Scroll within the panel for all 11 ·
Semantic Vocabularies 1
JSON-LD contexts give the data shared meaning across APIs. We profile them because semantics are what let a machine reconcile 'customer' here with 'customer' somewhere else.
JSON-LD contexts and semantic vocabularies used across these APIs.
Mailboxlayer Context
JSON-LDSpectral Rules 2
Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.
mailboxlayer API Rules
SPECTRALmailboxlayer API Rules
SPECTRALJSON Schema 2
Standalone JSON Schema definitions describe the data models behind the API. We profile them so the shapes are validatable on their own — useful long after a single request is forgotten.
Standalone JSON Schema definitions for this provider's data models.
mailboxlayer Email Check Result
JSON SCHEMAmailboxlayer Error Response
JSON SCHEMAJSON Structure 1
JSON Structure captures the data shapes in a form built for tooling — a complement to JSON Schema that keeps the model machine-legible.
JSON Structure definitions describing this provider's data shapes.
Mailboxlayer Check Result Structure
JSON STRUCTUREExamples 6
Real request and response payloads are what turn a spec from abstract into obvious — and they're one of the twelve things an agent needs to call an API correctly on the first try.
Example request and response payloads for these APIs.
Security Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Agentic Access 1
An x-agentic-access contract marks which operations are safe for an agent to run on its own and which need a human in the loop. It is the difference between an API an agent can use and one it can use safely.
Recommended x-agentic-access execution contracts for AI agents.
Use Cases 6
What developers actually build with this provider — captured so the catalogue answers 'what is this for', not just 'what does this expose'.
What developers build with this provider.
Signup Form Validation
Catch typos and disposable addresses at signup before they hit your user database.
List Hygiene
Clean existing email marketing lists to lift deliverability and sender reputation.
Lead Enrichment
Enrich CRM and lead-capture records with deliverability scores and role flags.
Fraud And Abuse Prevention
Block disposable email providers commonly used for trial abuse and chargebacks.
Transactional Email Hygiene
Reduce hard-bounces from order receipts, password resets, and notifications.
B2B Sales Qualification
Separate role addresses and free-provider addresses from individual corporate inboxes.
Integrations 7
Pre-built integrations with other platforms tell you where this provider already fits in a stack.
Pre-built integrations with other platforms and tools.
PostHog
Plugin scoring incoming PostHog user emails via the mailboxlayer API.
Fortinet FortiSOAR
Connector for incorporating email verification into security orchestration playbooks.
Laravel
Multiple community Laravel packages wrap mailboxlayer for PHP web applications.
Symfony
Symfony bundle for mailboxlayer-backed email validation.
Node.js / TypeScript
Node and TypeScript client libraries for serverside email verification.
Ruby
Ruby client gem.
Delphi
Delphi sample demonstrating the API for desktop application validation.
Scroll within the panel for all 7 ·
Solutions 5
Packaged solutions the provider offers on top of the raw API surface.
Packaged solutions this provider offers.
Free
100 requests/month, HTTP only, no support, no catch-all detection.
Basic
$14.99/mo for 5,000 requests; HTTPS, catch-all detection, standard support.
Professional Plus
$74.99/mo for 50,000 requests; adds bulk endpoint (25 emails).
Enterprise Plus
$249.99/mo for 250,000 requests; adds bulk endpoint (100 emails) and richer SLAs.
Custom
Contact sales for higher volumes and bespoke arrangements.
Resources
Every other property we hold for mailboxlayer — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 3
Portal, sign-up, and the first successful call
Agent Surfaces 1
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 2
Pagination, idempotency, versioning, errors, and events
Build 6
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 2
Status, limits, changes, and where to get help
Commercial 5
Pricing, plans, and the legal terms of use
Company 1
The organization behind the API
Other 1
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/mailboxlayer · machine-readable index on apis.io