Verify emails in Claude
Claude connects to SimpleVerifier's MCP server (https://simpleverifier.com/api/mcp) as a custom connector. After you sign in, Claude runs the live mailbox check when you ask about an address or paste a list, and reports valid, risky or invalid with the reason.
Setup
- You need a SimpleVerifier plan with API and MCP access. Claude's free plan can add one custom connector; on Team and Enterprise an owner adds it under Organization settings, Connectors.
- In claude.ai, go to Customize, then Connectors. Click + Add, then Add custom connector.
- Enter the name SimpleVerifier and the server URL https://simpleverifier.com/api/mcp, then click Continue.
- Leave the detected authentication settings as they are, click Continue, then Add.
- Connect the connector, sign in with Google on the SimpleVerifier screen and choose Allow.
- In Claude Code, run claude mcp add --transport http simpleverifier https://simpleverifier.com/api/mcp, then /mcp to sign in.
What people use it for
- Have Claude check a list of conference or webinar contacts before you write the follow-up.
- Let Claude Code verify the test addresses or seed data in a project before an email feature ships.
- Ask Claude to explain a bounce: it can check the domain's MX, SPF, DMARC and catch-all status.
Using the result
Route on the status field: valid means the mail server confirmed the mailbox, risky means delivery could not be confirmed (catch-all domain, role address, provider that hides mailbox status), invalid means it will bounce or is a throwaway address. Keep risky out of cold sequences unless you accept the bounce risk. Claude is told the same: it reports risky as risky and never upgrades an unconfirmed address to valid.
Full endpoint reference, error codes and an OpenAPI file are in the API docs. For lists of thousands of addresses, upload a CSV on the verify page instead.
Try it on your own list first
Upload a CSV and get 100 free checks in the dashboard, no card needed, to see the results before you connect Claude. The Claude setup itself needs a plan with API access.
Common questions
- Which plans include API access for Claude?
- API access comes with Pro, Business and Agency, listed on the pricing page; Starter covers CSV verification only. A key on a plan without API access gets a 402 that says so. Each key can make 120 calls a minute.
- Is SimpleVerifier in Claude's connector directory?
- Not yet. Add it as a custom connector with the steps above; it works the same way.
- Can I use an API key instead of signing in?
- In Claude Code and other clients that take a custom Authorization header, yes; /docs/mcp has the config. claude.ai signs in with OAuth.