usefulapiEnginemailer MCP server
Read Enginemailer subscribers, lists and campaigns; add subscribers, create and send campaigns. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.
What can I ask?
Turn on the Enginemailer connector, then ask in plain words. The AI picks the tools.
- Look up the subscriber jane@example.com and show her custom fields and lists.
- Add john@example.com to my Newsletter list with the source 'Signup from website'.
- How did my last delivered campaign perform: opens, clicks, bounces?
- Export the transactional email report for the last 30 days and give me the download link.
What you can do with Enginemailer in Claude and ChatGPT
For marketers and developers who send campaigns and transactional email with Enginemailer.
Look up a subscriber by email
Finds a subscriber by email and shows the status and all custom field values. Custom field definitions can be listed too.
Check campaign results or list unsent campaigns
Reads the results of a delivered campaign: sent, delivered, bounces, opens, clicks, unsubscribes and spam complaints. Also lists drafts and scheduled campaigns.
Add, update or unsubscribe a subscriber
Adds a subscriber with subcategories and custom fields, changes subcategories or custom fields, or unsubscribes a person from campaigns.
Changes dataCreate a campaign, pick recipients and send it
Creates a campaign draft, sets recipients to all subscribers or to chosen subcategories, and sends it now. Sending cannot be undone.
Changes dataSend a transactional email to one person
Sends one transactional email now to one recipient, with optional CC and BCC. It needs a sender address set up in Enginemailer.
Changes dataExport the transactional email report
Starts a CSV export of the transactional delivery report for a period of up to 60 days back, then checks it and gives the download link when done.
Changes dataHow do I connect Enginemailer?
Before you connect
The login page asks for your Enginemailer API key.
In Enginemailer open Manage account → API Keys and copy a key (you can create a separate key for this connection and revoke it any time). The key acts on your whole account, including sending email, so use it only with an assistant you trust. The Campaign tools need a paid Enginemailer plan. Your key is used only to call the Enginemailer 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 Enginemailer and this URL, then click Add:https://
enginemailer. usefulapi. io/ mcp - Claude opens the login page: enter your Enginemailer API key.
- In a chat, click + → Connectors and turn on Enginemailer.
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 Enginemailer and this URL, choose OAuth as the authentication, confirm the warning and create it:https://
enginemailer. usefulapi. io/ mcp - ChatGPT opens the login page: enter your Enginemailer API key.
- In Plugins, install Enginemailer, 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": {
"enginemailer": {
"url": "https://enginemailer.usefulapi.io/mcp"
}
}
} VS Code
Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"enginemailer": {
"type": "http",
"url": "https://enginemailer.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 Enginemailer 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 Enginemailer server only. Ask your AI to run enginemailer_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 enginemailer_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 enginemailer_upgrade before then undoes the cancel. Or write to support@usefulapi.io.
Tools 21
Show all 21 tools (the AI picks them for you)
Read only · 8
- Get subscriber
enginemailer_get_subscriberOne subscriber by email: id, status and all custom field values. - List subscriber categories
enginemailer_list_subscriber_categoriesThe subscriber category tree: each category with its subcategories (ids, names). Use the subcategory ids when adding or updating subscribers and when assigning campaign recipients. - List custom fields
enginemailer_list_custom_fieldsThe subscriber custom field definitions (key, name, type). Use the keys when adding or updating subscribers. - List undelivered campaigns
enginemailer_list_campaignsList campaigns that have NOT been delivered yet (drafts and scheduled ones): id, name, subject, sender and schedule. Delivered campaigns are not listed by the API; use enginemailer_get_campaign_stats with a known id. Needs a paid account. - Get campaign delivery stats
enginemailer_get_campaign_statsDelivery results of a DELIVERED campaign: emails sent, delivered, bounces, opens, unique opens, clicks, unique clicks, unsubscribes, spam complaints. Needs a paid account. - List campaign categories
enginemailer_list_campaign_categoriesThe categories that campaign recipients can be filtered by (id, name, description). Needs a paid account. - List campaign subcategories
enginemailer_list_campaign_subcategoriesThe subcategories of one campaign category (id, name, description); use these ids in enginemailer_assign_campaign_recipients. Needs a paid account. - Check transactional report export
enginemailer_check_transactional_report_exportStatus of a report export (Processing or Complete); when complete it includes the CSV download URL. POST /RESTAPI/V2/Submission/Report/CheckExport (read-only).
Changes data · 9
- Add subscriber
enginemailer_add_subscriberWRITE: add a subscriber to the account (optionally into subcategories, with custom field values). Only add people who consented to marketing email. Free accounts may insert 50 subscribers a day, paid accounts 10,000. - Update subscriber
enginemailer_update_subscriberWRITE: change an existing subscriber's subcategories and/or custom fields. subcategories_mode: append (default), remove (drop the given subcategories) or replace (the given list becomes the full list). custom_fields_mode: update_given (change only the given fields) or replace_all (default; fields not given are cleared). - Unsubscribe subscriber
enginemailer_unsubscribe_subscriberWRITE: unsubscribe a subscriber so they no longer receive campaigns. Reversing it needs the subscriber to opt in again in Enginemailer. - Create or update subscriber category
enginemailer_save_subscriber_categoryWRITE: create a subscriber category (category_id 0) or update one (its id), with subcategories (subcategory_id 0 creates one). Names and descriptions max 128 characters. - Create campaign (draft)
enginemailer_create_campaignWRITE: create a campaign DRAFT. Nothing is sent: assign recipients with enginemailer_assign_campaign_recipients, then send with enginemailer_send_campaign. The sender domain must be verified in Enginemailer; max 200 campaigns per account. Needs a paid account. - Assign campaign recipients
enginemailer_assign_campaign_recipientsWRITE: set who a campaign will go to: all subscribers, or the subscribers in the given subcategory ids (match_type any = OR, all = AND). Does not send anything. Needs a paid account. - Send campaign NOW
enginemailer_send_campaignWRITE, SENDS EMAIL TO CUSTOMERS NOW and cannot be undone: delivers the campaign to its assigned recipients immediately. The campaign needs at least one recipient and must not be scheduled or already delivered. Show the user the campaign and its audience and get their go-ahead first; set confirm to true only then. Needs a paid account. - Send transactional email
enginemailer_send_transactional_emailWRITE, SENDS ONE EMAIL NOW and cannot be undone: submits a transactional email to one recipient (plus optional CC/BCC). Needs a sender address on a verified domain; give either subject + content_html, or a template_id from the Enginemailer portal (the template supplies subject and sender name). Total message incl. attachments max 5 MB. Confirm the recipient and text with the user first; set confirm to true only then. - Start transactional report export
enginemailer_start_transactional_report_exportStart a CSV export of the transactional email delivery report for a period (start date at most 60 days back). Returns an export id; poll it with enginemailer_check_transactional_report_export. Creates a report file only; nothing is sent.
Your usefulapi plan · 4
- Usage status (free-tier meter)
enginemailer_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
enginemailer_request_featureTell usefulapi that the user needs something the Enginemailer 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+
enginemailer_upgradeGet a paid plan for Enginemailer (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
enginemailer_cancel_subscriptionCancel the caller's Enginemailer 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 enginemailer_upgrade later to undo the cancel before the period ends. Does not count against the meter.
FAQ
What can I do with Enginemailer in Claude or ChatGPT?
Look up a subscriber by email. Check campaign results or list unsent campaigns. Add, update or unsubscribe a subscriber. Create a campaign, pick recipients and send it. Send a transactional email to one person. Export the transactional email report. See what you can do for the details.
Is this an official Enginemailer product?
No. usefulapi is an independent service. It is not affiliated with or endorsed by Enginemailer. The server calls the Enginemailer API with your own Enginemailer access, so it sees only the data that your account can see.
Can I connect Enginemailer 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 Enginemailer API key. See Before you connect for where to find it.
Do I put my Enginemailer 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 Enginemailer 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 Enginemailer credentials?
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Enginemailer 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 Enginemailer.
Can the AI change my Enginemailer data?
Yes, if you approve it. 9 of the 17 Enginemailer tools can create or change data. The other 8 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 Enginemailer server only. Cancel any time: your paid plan then runs to the end of the paid period. Run enginemailer_usage_status to see how many calls you used.
How do I subscribe or cancel?
Ask the AI to run enginemailer_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 enginemailer_cancel_subscription. Your paid plan continues to the end of the paid period.
What if a Enginemailer tool that I need is missing?
Tell the AI what you wanted to do. It can send the request with enginemailer_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.