Mail7 MCP server
Email validation for AI assistants. This is an MCPserver that gives Claude, Cursor, Windsurf, Cline and any other MCP client four tools:verify a single address, clean a list, check a domain's SPF record, and audit adomain's whole mail configuration.
Honest by design: Mail7 answers Valid, Not Valid or Unknown, and the tooldescriptions tell the model in plain words that Unknown means "could not be verified",not "bad". An assistant using this server will not silently delete addresses it couldnot check.
Install
Node 18+ required. No install step - the server runs through npx.
Claude Code
claude mcp add mail7 --env MAIL7_API_KEY=your_key -- npx -y mail7-mcp
Claude Desktop (claude_desktop_config.json), Cursor (~/.cursor/mcp.json),and most other clients use the same shape:
{
"mcpServers": {
"mail7": {
"command": "npx",
"args": ["-y", "mail7-mcp"],
"env": { "MAIL7_API_KEY": "your_key" }
}
}
}
Get an API key at mail7.net/account. The server also runswithout one, but anonymous callers are limited to 5 checks per minute and a 25-addressfree bulk sample - not enough for real work.
| Variable | Default | Purpose |
|---|---|---|
MAIL7_API_KEY |
- | Raises rate limits, unlocks full bulk validation |
MAIL7_BASE_URL |
https://mail7.net/api |
Override the API endpoint |
Tools
| Tool | What it does |
|---|---|
validate_email |
One address: syntax, MX, disposable-domain check, live SMTP mailbox probe |
validate_emails |
Up to 50 addresses per call, with a Valid / Not Valid / Unknown summary |
check_domain |
Full mail-config audit graded A-F: MX, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, DNSSEC, BIMI |
check_spf |
SPF record, mechanisms, lookup count and misconfigurations |
Ask your assistant things like:
- "Is
[email protected]a real mailbox?" - "Clean this list of signups and tell me which ones bounce."
- "Why do our emails to customers land in spam? Check
ourdomain.com."
How results are shaped
validate_email and validate_emails return structured content alongside the text, soa client that supports structured tool output gets typed fields:
{
"email": "[email protected]",
"status": "Unknown", // "Valid" | "Not Valid" | "Unknown"
"valid": null, // true | false | null (null = Unknown)
"formatValid": true,
"mxValid": true,
"smtpValid": false,
"is_disposable": false,
"details": "Server accepts all addresses (catch-all) - status unknown"
}
check_domain returns a compact graded summary with a fix for every problem. To see theraw records of one part, call it again with section set to mx, spf, dkim,dmarc, mta_sts, tls_rpt, dnssec, bimi or domain.
Notes for large lists
Every address is a live SMTP conversation, so a check takes seconds, not milliseconds.validate_emails caps at 50 addresses per call on purpose - call it repeatedly with thenext chunk rather than pushing a whole file through one call, and never run two calls inparallel (the API serialises one bulk job per client).
Development
npm install
npm run build # -> dist/
node dist/index.js # speaks MCP over stdio
License
MIT. Part of the Mail7 integrations.
