Identity-first discovery

Find and verify work emailswith identity-firstdiscovery

Find and verify emails with alias resolution and multi-domain discovery. Map addresses to valid, existing identities.

~91%Success rate
11+Identity providers
MCPAgent-native
<10sAvg. response

Agent integration

One command. Any agent.

Install the MCP server in your preferred coding agent and start running finder and probe calls from the same workspace token.

the old technique

Why it doesn't work:

Servers today have adapted to prevent SMTP probing and this technique began to yield worse results as time went by -- relying on it can only be effective ~50% of the time. Unlike most providers, Relentless Identity has developed a new method that doesn't depend on these probes only. For a shorter explanation, read about why SMTP verification falls short. It returns valid identities regardless of catch-all status, finds alternative domains, and resolves aliases; the most recent and effective tool for large SaaS databases and complex workloads.

The best API as of today

While good tools exist, a pressing issue needed answering: Most results are imprecise and not accurate. Organizations adopting catch-all domain behavior and sitting behind gateways were increasing significantly. Relentless Identity is a modern, up-to-date response to all of this change. Read the clearer breakdown of identity verification vs. email verification if you want the decision rule in one place.

Alias resolution and multi-domain discovery

We're the only API that can reliably resolve detected aliases and find addresses across multi-domain organizations from a single, public-facing website domain.

How we compare

Built different.

Most companies relying on email miss on average 25% of their revenue due to poor data. Our API is built to interpret modern identity and email infrastructure stacks to return live, accurate data; helping with fraud prevention, marketing efforts and underwriting.

CapabilityMillionVerifierBounceBantrykitt.aiRelentless Identity
SMTP probing
Catchall detection
Precise Catchall Verification
MCP-native access for AI agents
Identity Provider Discovery
Alias Detection and Resolution
Multi-domain Identity Finder

Identity coverage

Supported identity providers.

Below are the identity providers we support

Microsoft Entra IDOktaOneLoginAuth0Ping IdentityGoogle WorkspaceJumpCloudKeycloakSalesforce IdentityDuo SSOSailPoint

Why it resolves better

Live verification, not stale lookup tables.

01

No database layer from previous results

Results are produced from live provider and mailbox checks instead of stale dumps, recycled enrichment tables, or purchased address inventories. Only caching is used for redundant requests to optimize for speed.

02

SMTP-only has blind spots

SMTP probing can surface deliverability but it cannot reliably map a mailbox to a real identity once gateways, catch-all behavior, and modern login stacks get involved.

03

Identity checks expose aliases

Relentless Identity correlates provider-side identity evidence with live routing signals, which is why it can resolve aliases and distinguish valid users from generic catch-all responses.

Built for modern outreach stacks

Who uses Relentless Identity?

Relentless Identity is built for teams that need a reliable answer about a specific person, not just a mailbox verdict. Sales and RevOps teams use it to find the right work email before outreach. Recruiting teams use it to verify candidate contacts. Fraud, underwriting, and onboarding teams use it when an email needs to be tied back to a real identity rather than a generic deliverability score.

The product is also designed for technical workflows. Developers can call the REST API, agents can use MCP, and data pipelines can keep the same response semantics across find-and-verify steps. If you are deciding whether you need list hygiene or identity-level confidence, start with the identity verification vs. email verification guide.

API playground

Integrate in minutes.

API wrappers and MCP clients available for seamless integration with a compact response body

Terminal - Direct API

POST /client/attempt

How it works

Three steps. Precise Response.

1

Submit

Provide either a name, company domain pair or an email address.

2

Classify

Performs domain discovery before verifying against the person or given identity.

3

Verify

For finder calls, it'll look for related email domains and for an identity across them. For individual probe calls, it'll confirm whether the particular identity exists or not for the given email domain.

FAQ

Common questions.

What is email identity verification?

It is a check that asks whether an address belongs to a real work identity, not just whether a mail server might accept a message. For more context, see the identity vs. email verification guide.

How does catch-all email verification work?

Catch-all domains accept mail broadly, so SMTP checks alone can be ambiguous. Relentless Identity combines provider, routing, and domain signals to narrow the result, and the gateway guide explains why this matters.

What is the difference between a finder and a verifier?

Finder starts with a person and a company domain, while Probe starts with a known email address. The Finder API workflow shows how the two steps fit together.

Does Relentless Identity support MCP?

Yes. MCP is part of the core product surface, so agents and IDEs can run the same workflows as the API. Read the MCP workflows article for the implementation pattern.