MailTester Email Verification

Measured conclusion: Alive, not deep-tested. L2 outcome: not_attempted.

Verify emails (valid/invalid/risky/unknown): MX, SMTP, catch-all, disposable. Free agent key.

Add to your agent

Copy this into your MCP client config:

{
  "mcpServers": {
    "MailTester Email Verification": {
      "url": "https://app.mailtester.com/mcp",
      "transport": "streamable-http"
    }
  }
}

Measured tools (9)

• get_api_key

  Get your own free API key for this server (no account needed; 25 email verifications per day). Optional: the verification tools already work without a key on a shared trial. Returns the key once — reconnect with 'Authorization: Bearer <api_key>' for your own quota and the list tools.

  Parameters:

  • name — string — Your agent's name.
  • contact — string — Optional operator email or URL.
  • purpose — string — What you verify emails for.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• get_credit_balance

  Get the current credit balance and a short usage summary for the account.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• list_lists

  List the user's bulk verification lists/jobs, most recent first.

  Parameters:

  • limit — integer — Maximum number of lists to return.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• get_list

  Get the details of a single bulk verification list by its id.

  Parameters:

  • list_id (required) — integer — The id of the bulk verification list.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• explain_result

  Explain what a verification status or reason means in plain English, with a send recommendation. Covers valid, invalid, catch-all/accept-all, unknown, greylisted, disposable, role, free, spam-trap, abuse, do-not-mail, no-mx, disabled, and network. Use when a user asks what a result means.

  Parameters:

  • term (required) — string — The status/reason to explain, e.g. 'catch-all', 'GREYLISTED', 'unknown', 'role'. Case-insensitive.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• verify_email

  Verify the deliverability of a single email address. Returns a verdict (valid, invalid, risky, unknown). Costs 1 credit.

  Parameters:

  • email (required) — string — The email address to verify.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• verify_batch

  Verify a batch of email addresses (up to 25 per call with an agent key). Returns per-email verdicts and saves a list. Costs 1 credit per email.

  Parameters:

  • emails (required) — array — Email addresses to verify.
  • name — string — Optional label for the saved list.

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• estimate_cost

  Estimate the credit cost of a verification before running it, and whether the user can afford it. Provide either a count of emails, a list_id to re-verify, or an operation ('single'/'finder'). Always quote this before proposing anything billable.

  Parameters:

  • emails — integer — Number of emails to verify (1 credit each).
  • list_id — integer — Estimate re-verifying an existing list by its id.
  • operation — string — Operation type: bulk/single (1 credit) or finder (3 credits).

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

• get_batch_status

  Get the progress and status of a bulk verification list/job by id.

  Parameters:

  • list_id (required) — integer

  Hints: read-only not declared · destructive not declared · idempotent not declared · open-world not declared

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Measured by MCPYP probing. Untested fields are omitted, never estimated. Listing is always free; MCPYP never proxies calls or stores user tokens.