uChecker

What is uChecker?

uChecker is an email verification service that exposes a Model Context Protocol (MCP) server, letting AI agents validate email addresses directly inside their workflows. Instead of writing REST API integration code, you connect uChecker to MCP-compatible clients like Claude Code or Cursor, and the agent handles validation natively. Each check returns a status of Good, Bad, or Unknown, along with a breakdown of syntax, MX records, SMTP probe results, disposable-domain flags, and role-address detection. The service also includes free SPF, DKIM, and DMARC checkers, and it is strictly an email verification tool—not generative AI.

Who it's for

• AI workflow builders — developers wiring agents into CRM enrichment, lead triage, or campaign prep who want validation without custom API glue.
• Sales and marketing operations teams — people who need clean contact lists before outreach, where a typo domain or a dead mailbox costs real time and sender reputation.
• Support and customer-facing staff — agents that parse inbound requests or hand-typed addresses and need to catch invalid or disposable domains before a customer slips through.

Key features

MCP server for agent-native validation

uChecker speaks the Model Context Protocol over a streamable HTTP endpoint. Add it to Claude Code, Cursor, VS Code, or any MCP-compatible client with a single configuration block, and your agent can call validation tools as if they were built-in. No REST endpoints to wire up, no custom parsing logic.

Bulk validation with task management

The validate_emails tool handles up to 10,000 addresses per call, and companion tools like wait_for_task, get_task_status, and get_task_results let the agent track progress and filter results by Good or Bad status. Task analytics break down deliverability and rejection reasons, and export_results produces CSV or clean/bad lists on demand.

Detailed verification breakdown

A check returns far more than a binary valid/invalid. You get syntax pass/fail, MX record presence, the mail server's response to an SMTP probe of that specific mailbox, disposable or catch-all domain flags, and role-address detection. That granularity matters: a catch-all domain may confirm an address that doesn't actually exist, and a role address like support@ is real but useless for cold outreach.

Transparent pricing and free tools

Pricing matches the API model: 1 email = 1 credit, and syntactically invalid addresses cost nothing. The dashboard exposes your credits balance and account-wide statistics, while SPF, DKIM, and DMARC checkers are available at no charge.

What stands out

An agent that validates before it stores is an agent that stops guessing.

The core insight is that a language model cannot distinguish [email protected] from [email protected]—both look equally plausible. uChecker closes that gap by giving the agent a real SMTP verification result instead of a probabilistic guess. The agent can then decide whether to keep a contact, flag it for review, or ask for clarification, all within its own reasoning loop. That turns email validation from a separate manual step into an integrated part of the agent's decision-making.

Worth checking out if…

You are building agentic workflows that touch email addresses—whether enriching a CRM with fresh leads, triaging inbound requests where a domain typo means a lost customer, or preparing a campaign where dead addresses damage sender reputation. If you already use MCP-compatible tools and want validation that runs as a background task rather than a blocking step, uChecker fits naturally. The free SPF, DKIM, and DMARC checkers also make it a low-cost addition to any deliverability toolkit.