usefulapiMailBluster MCP server
Manage MailBluster leads, custom fields, products and orders: look up, add and update records. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.
What can I ask?
Turn on the MailBluster connector, then ask in plain words. The AI picks the tools.
- Look up the lead customer@example.com and show their contact details.
- List the orders recorded for my shop with their totals.
- Which products have I registered for my shop's sales tracking?
- Add customer@example.com as a new lead with the first name Pat.
What you can do with MailBluster in Claude and ChatGPT
For online shop owners and marketers who keep leads, products and orders in MailBluster.
Look up a lead by email
The AI gets one lead by email address and shows name, custom fields, timezone, subscribed and opt-in status, tags and dates.
Add a new lead or update an existing one
The AI adds a lead, which is not subscribed to email unless you say the person gave consent, or changes a lead's name, custom fields, tags or timezone.
Changes dataAdd a custom lead field
The AI lists the custom lead fields with their merge tags and creates a new one. This changes the data model of the brand but sends nothing.
Changes dataReview order records with their totals
The AI lists order records with currency, total price, customer lead and line items, and reads one order. These are tracking records only.
Check product records or register and rename one
The AI lists the product records used for order tracking, reads one, registers a new product with your own id and name, or renames a product.
Changes dataRecord an order or correct an order record
The AI records an order as a tracking record, with no payment and no email. It can also change an order's campaign, currency, total or items.
Changes dataHow do I connect MailBluster?
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.
Claude claude.ai · Desktop
- Open Customize → Connectors, then click + Add → Add custom connector.
- Enter the name MailBluster and this URL, then click Add:https://
mailbluster. usefulapi. io/ mcp - Claude opens the login page: enter your MailBluster API key.
- In a chat, click + → Connectors and turn on MailBluster.
Team and Enterprise: an Owner adds the connector for the organization first.
ChatGPT chatgpt.com
- Open Plugins, click +, then Add custom MCP server.
- Enter the name MailBluster and this URL, choose OAuth as the authentication, confirm the warning and create it:https://
mailbluster. usefulapi. io/ mcp - ChatGPT opens the login page: enter your MailBluster API key.
- In Plugins, install MailBluster, then choose it in a chat.
No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.
Claude Code
Run this command, then run /mcp in Claude Code to log in:
Cursor
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"mailbluster": {
"url": "https://mailbluster.usefulapi.io/mcp"
}
}
} VS Code
Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"mailbluster": {
"type": "http",
"url": "https://mailbluster.usefulapi.io/mcp"
}
}
} Codex
Run these commands. The second one opens the login page:
Other clients
Windsurf, Cline, Zed and other MCP clients: add this URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser.
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.
Pricing
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 50 tool calls / month |
| Proper user | $9/mo · $90/yr | 10,000 tool calls / month |
| Pro+per user | $39/mo · $390/yr | 100,000 tool calls / month |
Each paid plan covers this MailBluster server only. Ask your AI to run mailbluster_upgrade and choose Pro or Pro+, billed monthly or yearly (it returns a Stripe Checkout link). If you already have Pro, ask to change it to Pro+. The change requires your confirmation, keeps your billing interval and charges the price difference for the rest of the period immediately. Cancel any time with mailbluster_cancel_subscription: your paid plan continues to the end of the paid period, with no refund for the current period, and asking to resume the same plan with mailbluster_upgrade before then undoes the cancel. Or write to support@usefulapi.io.
Tools 17
Show all 17 tools (the AI picks them for you)
Read only · 6
- List custom lead fields
mailbluster_list_fieldsList 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 lead
mailbluster_get_leadGet 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)}. - List products
mailbluster_list_productsList 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 product
mailbluster_get_productGet one product record by the id you registered it under. - List orders
mailbluster_list_ordersList 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 order
mailbluster_get_orderGet one order record by the id it was created with.
Changes data · 7
- Create custom lead field
mailbluster_create_fieldWRITE: 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. - Create lead
mailbluster_create_leadWRITE: 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). - Update lead
mailbluster_update_leadWRITE: 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)}. - Create product
mailbluster_create_productWRITE: register a product record (your own id plus a name) so orders can reference it. Sends nothing to anyone and charges nothing. - Update product
mailbluster_update_productWRITE: rename a product record. - Create order record
mailbluster_create_orderWRITE: 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. - Update order record
mailbluster_update_orderWRITE: 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.
Your usefulapi plan · 4
- Usage status (free-tier meter)
mailbluster_usage_statusReport 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. - Request a missing feature
mailbluster_request_featureTell 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. - Upgrade to Pro or Pro+
mailbluster_upgradeGet a paid plan for MailBluster (the free tier caps monthly usage). Pro: 10,000 tool calls a month, for normal use — plan "monthly" ($9/month) or "yearly" ($90/year, 2 months free). Pro+: 100,000 tool calls a month, for automations and heavy use — plan "plus" ($39/month) or "plus_yearly" ($390/year). Without a plan it returns both Pro and Pro+, each with a payment link, for the user to choose; with a plan, one link. An existing Pro subscription changes to Pro+ in place: call without confirm first, as the reply states the exact charge for this account (the price difference for the rest of the period, or in a free Pro trial the full Pro+ price, as the trial ends); then call with confirm: true. Cancel any time: the plan then runs to the end of the paid period, so it also suits a one-time job. A link opens Stripe Checkout in the browser; after payment the account upgrades automatically. Does not count against the meter. - Cancel the Pro subscription
mailbluster_cancel_subscriptionCancel the caller's MailBluster 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 mailbluster_upgrade later to undo the cancel before the period ends. Does not count against the meter.
FAQ
What can I do with MailBluster in Claude or ChatGPT?
Look up a lead by email. Add a new lead or update an existing one. Add a custom lead field. Review order records with their totals. Check product records or register and rename one. Record an order or correct an order record. See what you can do for the details.
Is this an official MailBluster product?
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.
Can I connect MailBluster to Claude or ChatGPT?
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.
What do I need to connect?
The login page asks for your MailBluster API key. See Before you connect for where to find it.
Do I put my MailBluster key or an Authorization header in the client config?
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.
How do you keep my MailBluster credentials?
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.
Can the AI change my MailBluster data?
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.
What does it cost?
The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with 10,000 tool calls / month. Pro+ costs $39/mo or $390/yr, with 100,000 tool calls / month. Each subscription covers this MailBluster server only. Cancel any time: your paid plan then runs to the end of the paid period. Run mailbluster_usage_status to see how many calls you used.
How do I subscribe or cancel?
Ask the AI to run mailbluster_upgrade and choose Pro or Pro+, billed monthly or yearly: it returns a Stripe Checkout link. If you already have Pro, ask to change it to Pro+. After you confirm, your existing subscription changes in place, keeps its billing interval and charges the price difference for the rest of the period immediately. To cancel, run mailbluster_cancel_subscription. Your paid plan continues to the end of the paid period.
What if a MailBluster tool that I need is missing?
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.
Which AI clients can I use?
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.