Email validation APIs you can pay per call

What email validation APIs do

An email validation API helps a caller decide how to handle a supplied email address. Validation can start with the structure of the string and continue through the domain's DNS and mail configuration, disposable-domain flags, role-account flags or other advertised risk signals. These observations are useful for form feedback and data quality, but they do not establish that a person owns an inbox or will receive a future message.

The decision depends on the stage of the workflow. A form can ask for a correction when the input is malformed. An import can preserve an unknown result for review. A sending-domain audit can identify authentication configuration that needs attention. The domain is a different subject from the individual recipient: a sender's SPF or DMARC policy does not prove that a particular destination mailbox exists.

Keep the submitted address, any suggested spelling change and the raw validation flags separate. A provider typo suggestion can name a different domain and therefore a different recipient. Treat it as a candidate correction. Do not silently replace a contact merely because the new string looks more familiar or a top-level score improved.

Use evidence levels in the result schema. Syntax can be valid while DNS information is unavailable. A domain can have mail infrastructure while the individual mailbox remains unknown. A disposable or role-based label is a category, rather than proof of abuse or a personal identity. An agent needs a bounded policy for accepting, asking for correction, reviewing or retrying the record without converting an unknown into a permanent invalid label.

Compare the returned data, scope and limitations

Individual address checks evaluate a supplied recipient. Batch checks evaluate several addresses under a documented request limit. Sending-domain reports evaluate authentication or mail configuration. Those outputs stay separate so a cheaper domain audit cannot supply the quote for evaluating an individual address.

The response contract matters more than the word deliverability. A copy grader can inspect spam-risk phrases without examining any recipient. A domain finder can discover an email or company without validating the address your application already has. DNS lookup, message generation, inbox rental and a paid-work acceptance receipt also have distinct subjects. The task selection excludes those neighboring tools.

A combined route can report syntax, mail-domain status and address-risk flags together. Keeping it in the individual-address type does not add an SMTP capability that its description does not advertise. When a provider explicitly excludes mailbox probing, preserve that limit in your own interface and downstream decisions. A return field named deliverable should be interpreted within the documented method.

AgentBIT, IPIntel.ai x402 Tools, Straelo Relay, RallyLive Intel and M0 Email Verification explicitly describe DNS or MX checks in their matched endpoint evidence. The source count concerns those declared signals, without establishing that a particular mailbox exists. Source and method descriptions should travel with the result when different providers' verdicts are compared.

Each price is the cheapest endpoint of that service for that kind of data: the same number wherever this page quotes it.

Compare 5 email validation services

Each row retains the selected task endpoint and its reference price. The ordering follows observed paying wallets for the service; it does not rank the accuracy of the underlying output.

$/CALL is the price of the endpoint named under it: the cheapest individual email syntax, mail-domain and risk checks and batch email-address checks endpoint of the service or, for a service without one, its cheapest email validation endpoint. Never the cheapest tool of a gateway. Other kinds of data have their own price in the tables below. EMAIL VALIDATION ENDPOINTS counts the email validation endpoints out of all the endpoints the service lists. BUYERS 30D counts distinct wallets that paid the whole service on-chain in 30 days, not only its email validation endpoints. "Generalist" marks a gateway that sells more than three unrelated kinds of tools: it is never called the cheapest.

How to choose an email validation endpoint

Decide what should block submission

A malformed address can prompt a correction. A temporary DNS failure may warrant review or a bounded retry. A disposable-domain flag can inform a policy without proving that the person is fraudulent. Define the handling of those cases before translating a provider score into rejection.

Keep recipient and sender checks distinct

Recipient validation takes an address and evaluates its technical signals. Sender authentication examines a domain's mail configuration. Store those results under different fields and compare costs per address or per domain accordingly. A content-risk grader belongs to a separate review of the message draft.

Evaluate incomplete evidence

Include known malformed strings, domains without mail records, ordinary addresses and cases expected to remain unknown. Compare raw flags and explanations instead of assuming that providers use identical meanings for valid, risky or deliverable. Proof of inbox control needs an appropriate challenge flow beyond a data-quality lookup.

Write an acceptance criterion

Choose the fields your next step requires before choosing a provider. Keep a small reviewed input set with straightforward cases, ambiguous cases and expected failures. Compare the raw fields and reason codes with that criterion rather than accepting a successful HTTP status as a complete result.

Keep provenance with the result

Store the input, selected route, observation time and provider-specific identifiers together. Preserve a missing value independently from zero, false or an explicit negative verdict. This helps an agent decide whether to retry, request clarification or accept a partial result without silently inventing certainty.

Test the operating limits

The monitored median uptime is 100% and the median selected quote is $0.005. Monitoring latency describes our checks, rather than a benchmark of your full paid workflow. Evaluate response size, timeout behavior and concurrency for a representative workload. Check whether a retry repeats a completed purchase and whether a later page or deeper product costs extra.

Choose by the output your workflow needs

Start with the response your next step can consume. The candidates below use the same type classification as the comparison table. The job quote belongs to the lowest priced endpoint of its requested types, with the originating path retained.

Individual email syntax, mail-domain and risk checks

Record which checks ran on the address: syntax, domain DNS or MX, disposable or role flags, or a provider score. A route that does not probe the mailbox cannot turn a pass into proof of delivery.

Candidates today, most buyers first: AgentBIT ($0.03/call, generalist, 71 buyers) · IPIntel.ai x402 Tools ($0.004/call, 25 buyers) · Straelo Relay ($0.005/call, 17 buyers) · M0 Email Verification ($0.005/call)

Batch email-address checks

A batch charge covers a list up to its stated size. Keep each address's verdict and reason, and compare the batch price with single checks at the list size you actually submit.

Candidates today, most buyers first: RallyLive Intel ($0.1/call, 5 buyers)

Sending-domain authentication and configuration

A sending-domain configuration report concerns domain infrastructure; it cannot replace validation of a supplied recipient.

Candidates today, most buyers first: IPIntel.ai x402 Tools ($0.001/call, 25 buyers) · RallyLive Intel ($0.05/call, 5 buyers)

What the providers describe

These paragraphs attribute output contracts and limitations to the provider. Reference prices follow the matching endpoint type rather than an amount embedded in a marketing description.

AgentBIT

AgentBit describes /v1/email/deliverability as an address deliverability and risk check at $0.03. It advertises syntax, mail-domain records, authentication checks, disposable-provider and role-account detection, plus a score, risk level and per-check details. The description explicitly says the checks use live DNS without mailbox pinging. Preserve that boundary when a caller interprets the score: it can support a technical review policy without confirming recipient identity or future delivery.

1 email validation endpoint of 25 · $0.03/call (GET /v1/email/deliverability) · ARB/Base/POL/SOL · uptime 30d 100% · 130 ms · 71 buyers in 30 days

IPIntel.ai x402 Tools

IPIntel's package separates /email-validate, at $0.004, from /domain-health, at $0.001. The address description advertises syntax, DNS/MX, disposable, role, free-provider and provider-typo checks, returning normalized input, a verdict, a risk score and structured flags. Domain health inspects DNS and mail configuration with issues and recommendations. Choose the input subject deliberately; a domain-health price cannot replace a recipient-validation quote even when the domain is extracted from that recipient.

2 email validation endpoints of 10 · $0.004/call (POST /email-validate) · Base · uptime 30d 100% · 256 ms · 25 buyers in 30 days

Straelo Relay

Straelo lists /email-validator/basic at $0.005. Its endpoint description explicitly limits the product to syntax, domain and MX checks without SMTP mailbox verification, and says it cannot prove mailbox existence or receipt. The separate /domain-health route checks general DNS, HTTP, redirects, TLS and response latency; that broader website-health product stays outside the email-specific type selection. Keep the advertised limitation visible when using a result to decide whether to request a correction.

1 email validation endpoint of 10 · $0.005/call (GET /email-validator/basic) · Base · uptime 30d 100% · 229 ms · 17 buyers in 30 days

RallyLive Intel

RallyLive describes /bulk/email-verify as checking up to twenty addresses per call, starting at $0.1. It advertises per-address syntax, MX, disposable, role and free-provider flags, a mail provider, verdict reasons and a summary. Its separate domain deliverability report starts at $0.05 and describes sender-authentication configuration. A batch quote is a request unit, not a price that should automatically be multiplied once for every address in that batch. Verify the input limit and preserve item-level outcomes.

2 email validation endpoints of 10 · $0.1/call (POST /bulk/email-verify) · Base/BSP · uptime 30d 100% · 217 ms · 5 buyers in 30 days

M0 Email Verification

M0's individual-address type starts at $0.005 across the captured verification and lead-validation routes. /v1/verify-email describes RFC-shaped syntax and live domain DNS resolution, explicitly excluding confirmation of mailbox existence. The lead-validation bundle adds mail-record, disposable-domain and role-account signals while also excluding person identity. Choose the route that exposes the evidence your workflow needs. A broader lead-check bundle does not turn the basic route's quote into the price of every enrichment step.

2 email validation endpoints of 3 · $0.005/call (POST /v1/verify-email) · Base · uptime 30d 94.2% · 434 ms · 0 buyers in 30 days

Cost per call and for a larger workload

The median selected route costs $0.005 per call. At the same input shape, 100,000 calls total $500.00. Use the generated table as a reference calculation, then measure how many requests produce one accepted result in your workflow.

Each service at the price of its main email validation endpoint, the one named in the table above.

A request can inspect one input, return several records or buy a bounded batch. Those units are different. Follow-up lookups, pagination, retries and a larger input can change the amount required. Preserve the exact endpoint, submitted parameters, returned quote and outcome so that a cheap submission is not mistaken for a cheap completed task. A variable-price route needs its own request quote; a priced neighbor cannot establish its total.

Set an explicit budget for each job and a stopping condition for repeated attempts. Separate an invalid input, an empty answer and an unavailable upstream in the result record. The provider's terms determine whether those outcomes incur a charge. Read the challenge for the exact request before authorizing a payment, and avoid estimating a task from the gateway's cheapest unrelated utility.

Inspect a request and its payment evidence

The public listing documents M0 Email Verification at POST /v1/verify-email. This endpoint has a reference quote of $0.005. Its description establishes syntax and domain DNS as the advertised evidence, with an explicit limit on mailbox existence. Read the current POST schema before constructing a JSON body; a catalog path alone does not establish the required body keys.

The listed method and description establish the advertised contract. This explanation does not reproduce an HTTP 402 challenge or certify a paid response. Open the linked service's payment evidence and obtain the challenge for the exact request before authorizing a payment. Preserve the resource, method, input and accepted payment together, then inspect the paid result against the advertised evidence level.

How this comparison is built

The comparison starts with services that are online and payment-ready, have a known price, a description of at least 80 characters and measured 30-day uptime of at least 90%. Task selection then inspects the documented endpoints. A phrase in the service description can identify a candidate without establishing that a captured route returns the desired output. Pages below the index threshold can still be read directly.

Provider output claims were reviewed against the public service and endpoint descriptions captured on October 22, 2026. They remain provider claims. Monitoring supplies operating figures and reference prices; it does not establish that a returned verdict matches the real state of the mailbox. Buyer counts describe observed paying wallets for the service, with the coverage limits explained on its linked page.

The endpoint classification supplies the comparison quote, per-type prices and job candidates. A row requires a fixed quote for individual-address or batch-address checks. Sending-domain authentication remains an adjacent type and cannot qualify a service or price its row. Keep the named path when comparing services: an adjacent product can have a different input, unit and evidentiary value even on the same host.

Questions

How to pay

Each service answers an unpaid call with HTTP 402 and its price; your agent signs a USDC payment on the listed network and retries. No API key, no account, no subscription. See what x402 is.