A free email validator for your browser, API and AI assistant

An incorrect email address can break a follow-up before you start writing it. Heffl's email validator checks one address at a time and reports the evidence behind its result. You can use the browser tool, call the JSON API, or connect a compatible AI assistant through MCP. None requires a Heffl account or API key.

What the validator checks

The engine checks address format and domain mail routing, then reports whether the address uses a known disposable provider, a personal email provider, or a role name such as support. It also suggests corrections for a small set of common domain typos. Suggestions never change your input automatically.

A role inbox and a Gmail address can be deliverable. These flags describe an address; they do not prove it is invalid.

Why the result can be unknown

Mail routing shows where a domain could receive messages. It does not establish whether a specific mailbox exists. SMTP checks run after format and routing checks pass. If the server cannot be reached or the response is inconclusive, mailbox status stays unknown.

When SMTP checks run, the engine asks the recipient server whether it accepts the address, without submitting an email. It can also compare a random recipient to detect accept-all behavior. Even a likely_deliverable result is evidence rather than a delivery guarantee.

Use the API

Send a JSON request to the public endpoint:

curl https://api.heffl.com/api/public-tools/email/verify \
  -H 'Content-Type: application/json' \
  -d '{"email":"[email protected]"}'

Read status, reason and checks together. Handle HTTP 429 by following Retry-After. There is no bulk endpoint, and anonymous access is rate limited.

Connect your assistant

Use the API and MCP guide for the remote server URL and client documentation. Your assistant must support remote MCP and you must enable the connector. Publishing a website does not automatically install it in your conversations.

Before you act on a result, read the difference between validation and mailbox verification.