# Free Email Verification API with Real SMTP Checks > Email verification API with real SMTP mailbox checks. A real-time email verification API for apps, forms, and AI agents — not syntax-only validation. --- ## Navigation - [Home](https://billionverify.com/index.md) **Product:** - [Features](https://billionverify.com/features.md) - [Email Verification](https://billionverify.com/email-verification.md) - [Bulk Email Verification](https://billionverify.com/bulk-email-verification.md) - [Email List Cleaning](https://billionverify.com/email-list-cleaning.md) - [Email Validation API](https://billionverify.com/email-validation-api.md) - [White Label](https://billionverify.com/whitelabel.md) - [Blog](https://billionverify.com/blog.md) - [Pricing](https://billionverify.com/pricing.md) --- **Page Language:** English --- # Email Verification API Real-time email verification API over HTTP with full SMTP mailbox checks — the accurate verification API for deliverability, not format-only validation. ![Email Verification API console with a bearer-auth POST request, a 200 OK pill and an uptime chart](/email-verification-api/email-verification-api.webp) Email Validation API ## Verify in Realtime Use a simple API call to verify addresses during signup, enrichment, AI agent workflows, or custom list-processing pipelines. Structured JSONReal-time responseSMTP verification [Get Started for Free](https://billionverify.com/auth/sign-in.md) ![Real Time Email Verification API returning a 200 OK response after an SMTP probe](/email-verification-api/real-time-email-verification-api.webp) ## Every verification API mode, one endpoint Every verification type is reachable through the same REST email verification API. ![Free Email Verification API mode cards for single, batch, file and SDK integration](/email-verification-api/free-email-verification-api.webp) ### Single Email Verification POST /verify — one real-time email verification API call with sub-3s response. Returns status, deliverability, quality score, and risk flags in one JSON object. ### Batch Verification POST /verify/bulk — verify up to 50 addresses per API call, synchronously. All results come back in a single API response, on the same schema the real-time email verification API uses for one address. ### Async File Processing POST /verify/file — submit CSV or Excel files to the API for background processing. Results are delivered via webhook callback when the API job completes. ### Official SDKs Type-safe client libraries for the verification API in Python, Node.js, Go, and PHP. Auto-retry on failure, full error handling, and identical response types across all languages. ## What every email verification API call includes Every real-time email verification API call runs the same multi-layer check automatically. ![Email Verification API Results showing status, deliverable and reason fields in a JSON response](/email-verification-api/email-verification-api-results.webp) [### Free Email Checker Check individual emails for validity, deliverability, and reputation. No account required.](https://billionverify.com/email-checker.md)[### Disposable Email Detection Identify and block temporary email services before they pollute your list.](https://billionverify.com/disposable-email-detection.md)[### Bounce Email Checker Detect emails likely to bounce before sending, protecting your sender reputation.](https://billionverify.com/bounce-email-checker.md) [### Catch-All Detector Identify accept-all mail servers that mask actual mailbox existence.](https://billionverify.com/catch-all-verifier.md)[### Role Account Filter Filter out generic role addresses like info@, support@, and admin@ that hurt engagement.](https://billionverify.com/role-account-detection.md) ## Webhook support in the verification API Receive API results asynchronously and query message history. ![Email Verification API Webhook delivering a signed callback event with a signature badge](/email-verification-api/email-verification-api-webhook.webp) Async Delivery ### Create Webhooks Register HTTP endpoints to receive API results the moment a job or batch completes. The API supports custom payloads, automatic retry on failure, and per-job or global configuration. - Job completion events with result summary - Automatic retry on failed delivery - Per-job or account-level configuration Message History ### Query Messages Access the full webhook event log to retrieve past API results, debug delivery failures, or replay missed notifications. API events are retained for 30 days. - Query events by job ID or date range - Replay missed or failed deliveries - 30-day event retention ## AI-native verification API integration Connect the API to every major AI client and SDK without writing verification logic from scratch. ![AI Email Verification API agent panel calling a verification tool through an MCP node](/email-verification-api/ai-email-verification-api.webp) [### MCP Server Verify emails in Claude Desktop and Cursor with natural language. Ask “is this address valid?” and get instant results from the same verification API — no API key setup, no code required.](https://billionverify.com/mcp.md)[### AI Agent Skills One-click skills for Claude, Manus, and other agent platforms. The email verification API runs automatically inside any workflow without manual configuration.](https://billionverify.com/agent-skills.md)[### Tool Use & REST Call the REST API directly from LangChain, CrewAI, any Anthropic or OpenAI SDK, or any HTTP client. The real-time email verification API returns structured JSON that parses without transformation — status, score, and flags included.](https://billionverify.com/email-verification-api.md) ## Explore More Features Every AI-native verification API tool in one platform. [### MCP Server Verify emails in Claude Desktop and Cursor with natural language. No code required.](https://billionverify.com/mcp.md)[### AI Agent Skills One-click skills for Claude, Manus, and other agent platforms. Automatic email validation in any workflow.](https://billionverify.com/agent-skills.md)[### Email Verification Verify individual addresses with real-time SMTP checks and instant results.](https://billionverify.com/email-verification.md) [### Bulk Email Verification Verify any size list with batched real-time checks or async queue processing.](https://billionverify.com/bulk-email-verification.md)[### Email List Cleaning Upload CSV or Excel files and clean lists of up to 200,000 addresses with live progress.](https://billionverify.com/email-list-cleaning.md) Inside the endpoint ## What the email verification API proves on every call An email verification API is only as useful as the evidence behind its response field. This one returns mailbox-level facts, not a syntax opinion dressed up as a verdict. ### Syntax and routing are the cheap layers, not the answer Every call to the email verification API normalizes the address, checks structure, and resolves the domain's mail exchanger records. Those two API layers are fast and cost nothing against the recipient, so they run first and short-circuit obvious garbage before the SMTP stage. A syntax-only API stops here and calls the result valid. That is the gap between a validation endpoint and a free email verification api that continues to the mailbox itself. ### SMTP is where the verification API earns its name The API opens a real SMTP conversation with the receiving server and tests the recipient path. No message body is sent, no confirmation link is clicked, and nothing lands in the person's inbox. Our free email verification api reads the server response far enough to separate an accepted recipient from a permanent rejection. This is what makes it a real-time email verification API rather than a DNS lookup with marketing copy attached. The evidence comes from the system that will actually accept or refuse your mail. ### Risk flags travel with the status, in the same response One JSON object from the API carries the deliverability status, a quality score, a risk level, reason codes, and the disposable, role-account, catch-all, and free-webmail flags. Your application does not need a second API call to learn why a result looks the way it does. Keeping flags beside the status is deliberate. An accepting role address and an accepting personal mailbox are both deliverable, and only your product knows which one belongs in this workflow. ### Inconclusive answers stay inconclusive Greylisting, provider deferrals, and rate limits are normal at API scale. The free email verification api returns unknown for those cases instead of promoting them to deliverable or demoting them to invalid. Retry logic belongs in your code, not hidden inside the endpoint. An API that silently guesses removes the one signal you need to decide whether to retry or route the record for review. Response fields ## Map each verification API status onto an application decision The API response is designed to be switched on directly. Each status maps to one action, and the API reason codes explain the borderline cases. ### deliverable — proceed The recipient path accepted the probe when the call ran. Accept the signup, write the contact, or queue the message, subject to whatever consent rules your product enforces. The free email verification api returns the same status field on the free tier as on paid volume, so behaviour you test with free credits is the behaviour you ship. ### undeliverable — reject or ask again A permanent failure from the API means the address will hard-bounce. In a signup form, show the field again with the API reason code. In a background job, suppress the record rather than deleting the original value. Never auto-correct the domain. A verification api can tell you an address fails; it cannot tell you which address the person meant. ### risky — apply your own policy Risky means the mailbox may accept mail while carrying a flag your product might care about. Read the reason codes: a disposable provider on a paid signup is a very different problem from a role address on a support form. Encode the policy once, at the point where you call our free email verification api, so every surface in the product treats the same API flag the same way. ### unknown — retry, do not discard The receiving provider gave the API an answer that proves nothing. Queue the address for a later API call rather than blocking the user or writing a false negative into your database. The real-time email verification API used inside a signup flow should degrade gracefully here: let the user through, verify again asynchronously, and act on the second API result. Integration patterns ## Where to call the email verification API in a real system Most API integrations use the same three touch points. Getting the placement of the API call right matters more than the SDK you choose. 1. 1 ### At the point of capture Call the API when an address is submitted — signup, checkout, lead form, or profile update. Verifying while the person is still on the page is the only moment a typo can be fixed by the person who made it, which is the strongest argument for an inline API call. Keep the call non-blocking beyond a short timeout. A free email verification api response usually arrives in one to three seconds, but your form should not fail because a receiving provider was slow. 2. 2 ### Inside the pipeline that already moves your data CRM sync jobs, enrichment workers, and ETL steps are natural homes for this free email verification api. Add the API call where records already flow, and store status, flags, and a checked-at timestamp as fields. For files rather than single records, the POST /verify/file API accepts CSV or Excel and calls your webhook when the job finishes, so batch API work does not need a long-lived connection. 3. 3 ### Inside AI agents and tools The MCP Server exposes our free email verification api to Claude Desktop and Cursor in natural language, and Agent Skills install it into agent platforms with one click. Both paths return the same structured JSON as the REST API. That matters for agent reliability: a model does not have to parse prose, and the tool cannot claim an address is fine when the underlying API said unknown. 4. 4 ### Around the send itself Freshness beats volume. Verify high-value recipients close to the send rather than trusting a status written months ago, and re-verify dormant records before they enter a campaign. For an entire list, [Bulk Email Verification](https://billionverify.com/bulk-email-verification.md) runs the same engine over a file so you are not rebuilding batching logic on top of the real-time endpoint. Honest limits ## Four things the email verification API does not claim The API response is trustworthy because its scope is narrow. Each of these belongs to a different tool or a different team, not to a verification API. ### It does not prove identity or consent An accepting mailbox says nothing about who controls it, where they work, or whether they agreed to be contacted. Shared aliases, forwarded addresses, and stale enrichment all produce deliverable API results attached to the wrong person. Use first-party data for identity and keep consent in your own system of record. No verification api can supply either. ### It does not guarantee inbox placement SMTP acceptance describes the recipient path at the moment of the API call. Whether your campaign reaches the inbox depends on sender reputation, authentication, content, and complaint history — all sender-side factors the API never observes. Verification removes address-level failures. Deliverability of the message itself is a separate programme with separate metrics. ### Catch-all domains remain uncertain A catch-all domain accepts every local part, so no free email verification api can prove that one guessed address exists there. The API returns the flag precisely so your code does not have to infer it. Route catch-all results to review rather than folding them into deliverable, especially on B2B lists built from name patterns. ### A result is an observation with a timestamp Mailboxes are closed, aliases retired, and domains migrated every day. The API reports what was true during the call, and that fact ages from the second the API responds. Store the checked-at time next to the status so downstream systems can decide when the evidence is too old to act on. Related surfaces ## How the verification API relates to the rest of the platform The same engine is exposed through several API surfaces. Choosing the right one is usually about who is asking, not about accuracy. ### One address, by hand When a person needs to inspect one result rather than automate thousands, the [Email Verifier](https://billionverify.com/email-verifier.md) runs the identical SMTP pipeline in the browser and shows every flag the API would return. It is the fastest way to sanity-check an address before writing code against the email verification api. ### A whole file at once When the work is a list rather than a stream, [Email List Cleaning](https://billionverify.com/email-list-cleaning.md) applies the same rules across every row and preserves the reasons in the export. Files and API calls share one engine, so a row cleaned in bulk and an address checked through the verification api cannot disagree. ### The validation-first framing The [Email Validation API](https://billionverify.com/email-validation-api.md) page describes the same endpoint for teams who search for validation rather than verification, with the integration details written from that angle. The endpoint, the schema, and the SMTP evidence are identical; only the framing of the documentation differs. ## Frequently Asked Questions ### 1. How fast is the email verification API? Cached API results return in under 200ms. Full SMTP verification completes in 1–3 seconds on average, which is what makes this usable as the real-time email verification API inside a form. The API supports up to 6,000 single verification requests per minute and 1,500 batch requests per minute. ### 2. How do I integrate the email verification API? The verification API uses standard REST calls with JSON responses. Official SDKs are available for Python, Node.js, Go, and PHP. Most API integrations complete in under 30 minutes. The MCP Server and Agent Skills require no code at all — install once and the real-time email verification API works in any supported AI client. ### 3. What does the email verification API cost? The Starter plan is $20 for 20,000 credits at $0.001 per email — no monthly fees, you only pay for what you use. Volume pricing scales down to $0.00035 per email at 1M credits. A free email verification api tier provides 20 free credits every day you log in, up to 600 a month, with no credit card required. ### 4. What does each verification API response include? Every API response includes the verification status (deliverable, undeliverable, risky, or unknown), a quality score from 0–100, a risk level, and reason codes. Disposable email flag, role account flag, catch-all detection, and typo correction suggestions are also included. ### 5. Is the verification API secure? All API requests use HTTPS. API key authentication is required on every API call, and IP whitelisting is available for additional security. BillionVerify is fully GDPR and CCPA compliant with automatic data deletion after processing. ### 6. How do AI agents and LLMs use this verification API? AI agents connect through the MCP Server (natural language in Claude and Cursor), pre-built Agent Skills (one-click install for Claude and Manus), or direct REST calls from LangChain, CrewAI, or any Anthropic or OpenAI SDK. Every path hits the same email verification api and returns the same structured JSON — no response transformation needed. ### 7. What is the difference between an email validation API and an email verification API? An email validation API and an email verification API usually refer to the same endpoint — one that checks whether an address is real and deliverable. BillionVerify uses SMTP-level verification, confirming the mailbox exists on the receiving server, rather than DNS or syntax validation alone. The single /verify endpoint returns status, quality score, disposable flag, role account flag, and catch-all detection in one JSON response. Email Verification API ## Get your API key One endpoint for every verification type. MCP Server and Agent Skills included. A free email verification api tier gives you 20 credits every day you log in, up to 600 a month, no credit card required. [Try the Email Checker Free](https://billionverify.com/auth/sign-in.md) 600 free credits monthly · Native MCP Server integration · No credit card required 99.9% Accuracy Real-time API Speed $0.00014 Per Email 600/mo Free Forever --- ## Sitemap **Product:** - [Pricing](https://billionverify.com/pricing.md) - [Features](https://billionverify.com/features.md) - [Email Verification](https://billionverify.com/email-verification.md) - [Bulk Email Verification](https://billionverify.com/bulk-email-verification.md) - [Email List Cleaning](https://billionverify.com/email-list-cleaning.md) - [Email Validation API](https://billionverify.com/email-validation-api.md) - [White Label](https://billionverify.com/whitelabel.md) **Methods:** - [Email Checker](https://billionverify.com/email-checker.md) - [Disposable Email Detection](https://billionverify.com/disposable-email-detection.md) - [Bounce Email Checker](https://billionverify.com/bounce-email-checker.md) - [Catch-All Verifier](https://billionverify.com/catch-all-verifier.md) - [Role Account Detection](https://billionverify.com/role-account-detection.md) **Email Tools:** - [Email Extractor](https://billionverify.com/email-extractor.md) - [Email Deliverability Test](https://billionverify.com/email-deliverability-test.md) **Google Maps:** - [Google Maps Overview](https://billionverify.com/google-maps.md) - [Google Maps Email Extractor](https://billionverify.com/google-maps/google-maps-email-extractor.md) - [Google Maps Leads Scraper](https://billionverify.com/google-maps/google-maps-leads-scraper.md) - [Google Maps Email Finder](https://billionverify.com/google-maps/google-maps-email-finder.md) - [Outscraper Email Verification](https://billionverify.com/google-maps/outscraper.md) - [Scrap.io Email Verification](https://billionverify.com/google-maps/scrap-io.md) - [Apify Email Verification](https://billionverify.com/google-maps/apify.md) **Cold Email:** - [Cold Email Overview](https://billionverify.com/cold-email.md) - [GMass Email Verification](https://billionverify.com/cold-email/gmass.md) - [Instantly Email Verification](https://billionverify.com/cold-email/instantly.md) - [Smartlead Email Verification](https://billionverify.com/cold-email/smartlead.md) - [Lemlist Email Verification](https://billionverify.com/cold-email/lemlist.md) - [Mailshake Email Verification](https://billionverify.com/cold-email/mailshake.md) - [Reply.io Email Verification](https://billionverify.com/cold-email/reply-io.md) **B2B Leads:** - [B2B Leads Overview](https://billionverify.com/b2b-leads.md) - [Apollo Email Verification](https://billionverify.com/b2b-leads/apollo.md) - [Hunter Email Verification](https://billionverify.com/b2b-leads/hunter.md) - [ZoomInfo Email Verification](https://billionverify.com/b2b-leads/zoominfo.md) - [Lusha Email Verification](https://billionverify.com/b2b-leads/lusha.md) - [LinkedIn Sales Navigator](https://billionverify.com/b2b-leads/linkedin-sales-navigator.md) - [Snov.io Email Verification](https://billionverify.com/b2b-leads/snov-io.md) **Local Business:** - [Local Business Overview](https://billionverify.com/local-business.md) - [Yellow Pages Email Verification](https://billionverify.com/local-business/yellow-pages.md) - [Yelp Email Verification](https://billionverify.com/local-business/yelp.md) - [Angi Email Verification](https://billionverify.com/local-business/angi.md) - [Local Business List Cleaning](https://billionverify.com/local-business/local-business-email-list-cleaning.md) **B2B Agency:** - [B2B Agency Overview](https://billionverify.com/b2b-agency.md) - [Clutch Email Verification](https://billionverify.com/b2b-agency/clutch.md) - [G2 Email Verification](https://billionverify.com/b2b-agency/g2.md) - [Trustpilot Email Verification](https://billionverify.com/b2b-agency/trustpilot.md) - [Agency Email Finder](https://billionverify.com/b2b-agency/agency-email-finder-workflow.md) **Integrations:** - [Integrations Overview](https://billionverify.com/integrations.md) - [Mailchimp Integration](https://billionverify.com/integrations/mailchimp.md) - [HubSpot Integration](https://billionverify.com/integrations/hubspot.md) - [Salesforce Integration](https://billionverify.com/integrations/salesforce.md) - [SendGrid Integration](https://billionverify.com/integrations/sendgrid.md) - [Klaviyo Integration](https://billionverify.com/integrations/klaviyo.md) - [ActiveCampaign Integration](https://billionverify.com/integrations/activecampaign.md) - [Zapier Integration](https://billionverify.com/integrations/zapier.md) - [Make Integration](https://billionverify.com/integrations/make.md) - [Pipedrive Integration](https://billionverify.com/integrations/pipedrive.md) - [Integrately Integration](https://billionverify.com/integrations/integrately.md) **Comparisons:** - [Comparisons Overview](https://billionverify.com/vs.md) - [Alternative to NeverBounce](https://billionverify.com/vs/neverbounce.md) - [Alternative to ZeroBounce](https://billionverify.com/vs/zerobounce.md) - [Alternative to Hunter](https://billionverify.com/vs/hunter.md) - [Alternative to Kickbox](https://billionverify.com/vs/kickbox.md) - [Alternative to EmailListVerify](https://billionverify.com/vs/emaillistverify.md) - [Alternative to MillionVerifier](https://billionverify.com/vs/millionverifier.md) - [Alternative to Emailable](https://billionverify.com/vs/emailable.md) - [Alternative to Bouncer](https://billionverify.com/vs/bouncer.md) - [Alternative to Verifalia](https://billionverify.com/vs/verifalia.md) - [Alternative to DeBounce](https://billionverify.com/vs/debounce.md) - [Alternative to Validity](https://billionverify.com/vs/validity.md) - [Alternative to VoilaNorbert](https://billionverify.com/vs/voilanorbert.md) - [Alternative to Reoon](https://billionverify.com/vs/reoon.md) **Resources:** - [Documentation](https://billionverify.com/docs.md) - [Blog](https://billionverify.com/blog.md) - [Email Glossary](https://billionverify.com/glossary.md) - [Benchmark Report](https://billionverify.com/benchmark.md) - [About](https://billionverify.com/about.md)