Check MailerCheck credits and lists, and run confirmed asynchronous email verification. For marketers and operations teams using MailerCheck to review email verification. Hosted by usefulapi — connect from Claude, ChatGPT, Cursor, or any MCP client.
Team and Enterprise: an Owner adds the connector for the organization first.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"mailercheck": {
"url": "https://mailercheck.usefulapi.io/mcp"
}
}
}Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"mailercheck": {
"type": "http",
"url": "https://mailercheck.usefulapi.io/mcp"
}
}
}No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.
Run these commands. The second one opens the login page:
Other MCP clients (Windsurf, Cline, Zed and more): add the URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser. Do not add an Authorization header: see Before you connect.
Read your connected account and remaining MailerCheck credits before submitting an email for verification.
mailercheck_account mailercheck_credits
Browse existing verification lists, then inspect a list’s processing status and aggregate result counts.
mailercheck_lists mailercheck_get_list
Confirm MailerCheck credit usage to submit one email for asynchronous verification. Keep its verification ID and read the status and result later, waiting between checks.
Changes data · mailercheck_verify_email mailercheck_verification_result
The login page asks for your MailerCheck API token.
In MailerCheck, open your profile → API → Create token. Copy the token when it is shown. Connecting only reads account details. Email verification spends your MailerCheck credits and requires confirmation. Only submit addresses you have permission to process. Changing the token creates a separate UsefulAPI billing identity.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your MailerCheck API token. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
Turn on the MailerCheck connector, then ask in plain words. The AI picks the tools.
| Tool | Type | What it does |
|---|---|---|
mailercheck_account | read | Read MailerCheck account Read the connected MailerCheck account name, ID and credit balance. Does not verify emails or spend verification credits. |
mailercheck_credits | read | Check MailerCheck credits Read the available MailerCheck verification credit balance without starting verification. |
mailercheck_lists | read | List MailerCheck verification lists Read one bounded page of list summaries, processing status and statistics. Does not create, verify or delete lists. Pagination stays on the MailerCheck API; no response links are followed. |
mailercheck_get_list | read | Read MailerCheck list status Read one existing list's verification status and aggregate result counts. Does not start or restart verification. |
mailercheck_verify_email | write | Start MailerCheck email verification Submit one email for asynchronous verification. Spends MailerCheck credits and requires confirm:true. This call is never retried. Read the returned verification ID with mailercheck_verification_result; wait between polls. If the response is lost, check MailerCheck before submitting again. |
mailercheck_verification_result | read | Read MailerCheck email verification result Read the status and result of a previously submitted asynchronous email check. Does not start new verification. Call once and wait before polling again; no automatic polling is performed. |
mailercheck_usage_status | Usage status (free-tier meter) Report the caller's current usage: the plan, calls used this month, the limit of the plan (the free monthly cap or the Pro fair use limit), remaining, and whether the limit is reached. Read-only; does not count against the meter. | |
mailercheck_request_feature | Request a missing feature Tell usefulapi that the user needs something the MailerCheck tools cannot do yet (a missing tool, field or filter). Call it only when the user asks for something none of the tools can do, and tell the user that you send the request. Do not call it for errors or for normal requests. Do not include personal data, credentials or customer records. Stored with the product name and the client type (for example Claude or Cursor), without the user's account. At most 5 requests per day. Does not count against the meter. | |
mailercheck_upgrade | Upgrade to Pro (unlimited*) Get Pro: unlimited tool calls (fair use limit: 10,000 a month) on MailerCheck (the free tier caps monthly usage). Plans: "monthly" — $9/month; "yearly" — $90/year (2 months free). Cancel any time: Pro then runs to the end of the paid period, so it also suits a one-time job. *A fair use limit applies. For heavy use (near Pro's limit): "plus" or "plus_yearly" — Pro+, $39/month or $390/year, unlimited tool calls (fair use limit: 100,000 a month); an existing Pro subscription changes to Pro+ in place (needs confirm: true; the price difference for the rest of the period is charged at once). Otherwise returns a short link to open in your browser (it opens Stripe Checkout); after payment the account upgrades automatically. Does not count against the meter. | |
mailercheck_cancel_subscription | Cancel the Pro subscription Cancel the caller's MailerCheck Pro subscription at the end of the paid period (no refund for the current period; Pro continues until then, then the free tier applies). Requires confirm: true. Run mailercheck_upgrade later to undo the cancel before the period ends. Does not count against the meter. |
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 50 tool calls / month |
| Proper user | $9/mo · $90/yr | Unlimited* |
*Pro fair use limit: 10,000 tool calls a month on this server. For more, write to [email protected].
Pro covers this MailerCheck server only. Subscribe with mailercheck_upgrade (it returns a Stripe Checkout link). Cancel any time with mailercheck_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running mailercheck_upgrade before then undoes the cancel. Or write to [email protected].
Check verification capacity. Review list verification progress. Verify a new email address. See what you can do for the details.
No. usefulapi is an independent service. It is not affiliated with or endorsed by MailerCheck. The server calls the MailerCheck API with your own MailerCheck access, so it sees only the data that your account can see.
Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.
The login page asks for your MailerCheck API token. See Before you connect for where to find it.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your MailerCheck API token. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the MailerCheck API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in MailerCheck.
Yes, if you approve it. 1 of the 6 MailerCheck tools can create or change data. The other 5 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with unlimited tool calls (fair use limit: 10,000 tool calls a month), for this MailerCheck server only. Cancel any time: Pro then runs to the end of the paid period. Run mailercheck_usage_status to see how many calls you used.
Ask the AI to run mailercheck_upgrade: it returns a Stripe Checkout link. To cancel, run mailercheck_cancel_subscription. Pro continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with mailercheck_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.
This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.
Need a tool this server does not have, or a connection to another system? We build custom integrations and MCP servers.