Manage MailBluster leads, custom fields, products and orders: look up, add and update records. Hosted by usefulapi — connect from Claude, 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": {
"mailbluster": {
"url": "https://mailbluster.usefulapi.io/mcp"
}
}
}Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"mailbluster": {
"type": "http",
"url": "https://mailbluster.usefulapi.io/mcp"
}
}
}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.
The login page asks for your MailBluster API key.
In MailBluster open your brand, go to Settings -> API keys and click Create new. The key works for that one brand; API keys need a plan that includes API access. Your key is used only to call the MailBluster API on your behalf; it is never shown to anyone.
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 MailBluster API key. 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.
| Tool | Type | What it does |
|---|---|---|
mailbluster_list_fields | read | List custom lead fields List the brand's custom lead fields: id, label and merge tag. Use the merge tags as keys of `fields` when creating or updating leads. GET /fields. |
mailbluster_create_field | write | Create custom lead field WRITE: create a custom lead field. The merge tag is the key used in lead `fields` and in email templates. Creating a field changes the brand's data model but sends nothing. POST /fields. |
mailbluster_get_lead | read | Get lead Get one lead by email address (the server computes the MD5 id MailBluster uses): name, custom fields, timezone, subscribed and opt-in status, tags, created/updated dates. MailBluster has no list-leads endpoint. GET /leads/{md5(email)}. |
mailbluster_create_lead | write | Create lead WRITE: add a lead (contact) to the brand. `subscribed` defaults to FALSE: the lead is stored but is not subscribed to email. Only set subscribed=true when the person has given consent to receive email from this brand (the user is responsible for lawful consent); this server never subscribes anyone on its own. No email is sent by this tool (double opt-in is not offered). If the lead already exists the call fails unless overwrite_existing=true, which replaces the stored data (then `subscribed` must be given explicitly). POST /leads. |
mailbluster_update_lead | write | Update lead WRITE: change an existing lead's name, custom fields, email, timezone, IP address, subscription flag or tags (send only what should change). `subscribed` is left alone unless you pass it; false unsubscribes the lead, true re-subscribes. Only set subscribed=true when the person has given consent to receive email from this brand (the user is responsible for lawful consent); this server never subscribes anyone on its own. PUT /leads/{md5(email)}. |
mailbluster_list_products | read | List products List product records (id, name, dates) the brand has registered for e-commerce tracking. Paged: the reply's meta has total and nextPageNo (null on the last page). GET /products. |
mailbluster_get_product | read | Get product Get one product record by the id you registered it under. GET /products/{product_id}. |
mailbluster_create_product | write | Create product WRITE: register a product record (your own id plus a name) so orders can reference it. Sends nothing to anyone and charges nothing. POST /products. |
mailbluster_update_product | write | Update product WRITE: rename a product record. PUT /products/{product_id}. |
mailbluster_list_orders | read | List orders List order records (id, currency, total price, customer lead, campaign, line items). These are records kept in MailBluster for tracking; no payment is involved. Paged: see meta.nextPageNo. GET /orders. |
mailbluster_get_order | read | Get order Get one order record by the id it was created with. GET /orders/{order_id}. |
mailbluster_create_order | write | Create order record WRITE: record an order (a tracking record: it does not take payment, charge a card or send email). The customer's email becomes a lead if none exists, and the lead's tags are merged. `customer.subscribed` is REQUIRED because MailBluster would otherwise default it to true: pass false unless the customer has consented to email. For a customer who already exists, the value may replace their stored subscription state. Only set subscribed=true when the person has given consent to receive email from this brand (the user is responsible for lawful consent); this server never subscribes anyone on its own. POST /orders. |
mailbluster_update_order | write | Update order record WRITE: change an order record's campaign, currency, total or items (send only what should change; `items`, when given, REPLACES all previous items). The customer cannot be changed here. No payment or email is involved. PUT /orders/{order_id}. |
mailbluster_usage_status | Usage status (free-tier meter) Report the caller's current free-tier usage this month: calls used, monthly limit, remaining, and whether the cap is reached. Read-only; does not count against the meter. | |
mailbluster_request_feature | Request a missing feature Tell usefulapi that the user needs something the MailBluster 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. | |
mailbluster_upgrade | Upgrade to Pro (unlimited) Subscribe to the Pro plan for UNLIMITED MailBluster tool calls (the free tier caps monthly usage). Choose monthly ($9/month) or yearly ($90/year — 2 months free) billing. Returns a Stripe Checkout link to open in your browser; after payment your account upgrades automatically. Does not count against the meter. | |
mailbluster_cancel_subscription | Cancel the Pro subscription Cancel the caller's MailBluster Pro subscription at the end of the paid period (no refund for the current period; unlimited calls continue until then, then the free tier applies). Requires confirm: true. Run mailbluster_upgrade later to undo the cancel before the period ends. Does not count against the meter. |
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 100 tool calls / month |
| Proper user | $9/mo · $90/yr | Unlimited |
Pro covers this MailBluster server only. Subscribe with mailbluster_upgrade (it returns a Stripe Checkout link). Cancel any time with mailbluster_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running mailbluster_upgrade before then undoes the cancel. Or write to [email protected].
No. usefulapi is an independent service. It is not affiliated with or endorsed by MailBluster. The server calls the MailBluster API with your own MailBluster access, so it sees only the data that your account can see.
The login page asks for your MailBluster API key. 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 MailBluster API key. 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 MailBluster 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 MailBluster.
Yes, if you approve it. 7 of the 13 MailBluster tools can create or change data. The other 6 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 100 tool calls / month. Pro costs $9/mo or $90/yr, with unlimited tool calls, for this MailBluster server only. Run mailbluster_usage_status to see how many calls you used.
Ask the AI to run mailbluster_upgrade: it returns a Stripe Checkout link. To cancel, run mailbluster_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 mailbluster_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, 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.