Manage Mail Blaze lists, subscribers, templates, campaigns and reports; send transactional email. 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": {
"mailblaze": {
"url": "https://mailblaze.usefulapi.io/mcp"
}
}
}Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"mailblaze": {
"type": "http",
"url": "https://mailblaze.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.
The login page asks for your Mail Blaze API public key.
Find it in Mail Blaze → your Profile menu → API Keys: create a key and copy the Public key. The key acts with full access to your account; you can revoke it there at any time. Your key is used only to call the Mail Blaze 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 Mail Blaze API public 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.
Turn on the Mail Blaze connector, then ask in plain words. The AI picks the tools.
| Tool | Type | What it does |
|---|---|---|
mailblaze_list_lists | read | List mailing lists List the account's mailing lists (name, uid, subscriber counts, defaults). Use the list uid in the other tools. Paged: page + per_page. |
mailblaze_get_list | read | Get a mailing list Get one mailing list by its uid: general settings, default sender, company details and counts. |
mailblaze_list_list_fields | read | List a list's custom fields List the fields of a mailing list (label, tag, type, required). The tags (EMAIL, FNAME, LNAME, custom ones) are the keys used when adding or updating subscribers. |
mailblaze_list_segments | read | List a list's segments List the segments defined on a mailing list (uid, name). A segment uid can be used when creating a campaign. |
mailblaze_list_subscribers | read | List subscribers List the subscribers of a mailing list (sets of 10 per page; use page to go on). Contains personal data (emails, names). |
mailblaze_get_subscriber | read | Get a subscriber Get one subscriber of a list by subscriber uid (status, fields, dates). |
mailblaze_find_subscriber_by_email | read | Find a subscriber by email Look up a subscriber in one list by email address. Returns the subscriber (with its uid) or a not-found error. |
mailblaze_add_subscriber | write | Add a subscriber WRITE, MAY SEND A CONFIRMATION EMAIL: add one subscriber to a mailing list. Depending on the list's settings Mail Blaze may send the person a confirmation (double opt-in) email. Only add people who agreed to receive your email. An email that is already on the list answers with a conflict error. |
mailblaze_add_subscribers_bulk | write | Add or update subscribers in bulk WRITE, MAY SEND CONFIRMATION EMAILS: add up to 100 subscribers to a mailing list in one request; an email already on the list is updated instead. Depending on the list's settings Mail Blaze may send confirmation emails. Only add people who agreed to receive your email. |
mailblaze_update_subscriber | write | Update a subscriber WRITE: update a subscriber's name or custom fields. Pass the subscriber's current email (Mail Blaze requires it) plus only the values to change. Does not change subscription status. |
mailblaze_unsubscribe_subscriber | write | Unsubscribe a subscriber WRITE: set a subscriber's status to unsubscribed so they receive no more campaigns from this list. By default Mail Blaze also adds the address to the account's local blacklist. Do this only when the person asked to stop (or a data-protection request requires it). The subscriber record is kept. |
mailblaze_resubscribe_subscriber | write | Resubscribe a subscriber WRITE: set a previously unsubscribed subscriber back to subscribed so campaigns reach them again. Only do this when the person asked to be re-added (consent). |
mailblaze_list_templates | read | List email templates List the account's email templates (uid, name). A template uid is needed to create a campaign. |
mailblaze_get_template | read | Get an email template Get one email template by uid (name and content). |
mailblaze_create_template | write | Create an email template WRITE: create an email template from HTML (the tool base64-encodes it). Mail Blaze requires the HTML to contain an unsubscribe link. Sends nothing. |
mailblaze_list_campaigns | read | List campaigns List the account's email campaigns (uid, name, status, dates). Use the campaign uid for details and reports. |
mailblaze_get_campaign | read | Get a campaign Get one campaign by uid: sender, subject, list, template, status and schedule. |
mailblaze_create_campaign | write | Create and schedule a campaign WRITE, SENDS EMAIL TO PEOPLE: create a campaign for a mailing list (or one of its segments) from an existing template and schedule it for send_at. Once it goes out it reaches every subscriber of the list or segment, may use sending credit and cannot be recalled. Confirm the list, segment, subject, template and send time with the user before calling. Needs a template uid (mailblaze_list_templates) and a list uid (mailblaze_list_lists). |
mailblaze_get_campaign_summaries | read | Get campaign report summaries Bulk report summary (sent, opens, clicks, bounces, unsubscribes) for up to 50 campaigns in one call. Read-only (it is a POST in the API only because of the id list). |
mailblaze_get_campaign_inbox_breakdown | read | Get a campaign's inbox breakdown Inbox-provider breakdown (e.g. Gmail, Outlook, Yahoo) of a campaign's delivery. |
mailblaze_list_campaign_events | read | List a campaign's opens, clicks, bounces or unsubscribes List the individual events of a campaign by kind: opens, clicks, bounces or unsubscribes. Cursor-paged: pass the reply's next_cursor back until it is null. For very large campaigns Mail Blaze answers 202 with a job_id; check it with mailblaze_get_report_job. |
mailblaze_get_subscriber_activity | read | Get a subscriber's activity Email activity (sends, opens, clicks, bounces) of one subscriber by email address, optionally limited to one list. Cursor-paged. |
mailblaze_get_report_job | read | Get a report job's status Status (and result when finished) of an asynchronous report job, as returned in a 202 reply with a job_id. |
mailblaze_list_transactional_emails | read | List transactional emails List the transactional emails sent through the account (uid, recipient, subject, status). Paged. |
mailblaze_get_transactional_email | read | Get a transactional email Get one transactional email by uid: recipient, subject, status and timestamps. |
mailblaze_send_transactional_email | write | Send a transactional email WRITE, SENDS ONE EMAIL NOW: send a single one-to-one email to one recipient through Mail Blaze. It leaves immediately, uses sending credit and cannot be recalled. Give either html (the body) or template_id (a transactional template, with merge_tags covering every tag in it), not both. Confirm the recipient and content with the user before calling. Not for bulk or marketing mail; use a campaign for that. |
mailblaze_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. | |
mailblaze_request_feature | Request a missing feature Tell usefulapi that the user needs something the MailBlaze 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. | |
mailblaze_upgrade | Upgrade to Pro (unlimited*) Get Pro: unlimited tool calls (fair use limit: 10,000 a month) on MailBlaze (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+, $19/month or $190/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. | |
mailblaze_cancel_subscription | Cancel the Pro subscription Cancel the caller's MailBlaze 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 mailblaze_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 API key | $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 Mail Blaze server only. Subscribe with mailblaze_upgrade (it returns a Stripe Checkout link). Cancel any time with mailblaze_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running mailblaze_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 Mail Blaze. The server calls the Mail Blaze API with your own Mail Blaze 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 Mail Blaze API public 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 Mail Blaze API public 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 Mail Blaze 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 Mail Blaze.
Yes, if you approve it. 8 of the 26 Mail Blaze tools can create or change data. The other 18 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 Mail Blaze server only. Cancel any time: Pro then runs to the end of the paid period. Run mailblaze_usage_status to see how many calls you used.
Ask the AI to run mailblaze_upgrade: it returns a Stripe Checkout link. To cancel, run mailblaze_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 mailblaze_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.