Mail Blaze
Manage mailing lists, subscribers, email campaigns and transactional emails through Mail Blaze.
Connect to Mail Blaze to manage subscriber lists, create and send email campaigns to segments, build email templates, track opens and clicks, and send transactional emails. Requires Mail Blaze account and API key.
Try asking Muse: "Send a welcome email campaign to new subscribers on my mailing list next Monday at 9am."
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Source: Found in the official MCP Registry (io.usefulapi/mailblaze) · First listed October 29, 2026
Last 24 hours
Each bar is one check, every 15 minutes. Green means it answered. Last checked 1 h ago.
Is it safe to connect?
What Muse can see: It does not ask you to sign in, so it cannot see your accounts. It only sees what Muse sends it from your request.
Before it acts: Read what Muse plans to do before you approve it, and remove the app from Muse when you stop using it.
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How to add it to Muse
Not in Muse's Connectors list yet, but Muse can still use it. Copy the request below and paste it into Muse. Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.
https://mailblaze.usefulapi.io/mcpNot in Muse's Connectors list yet. Muse can still use it: its page gives you a request to paste into Muse.
Also use it in ChatGPT or Claude
Mail Blaze is a remote MCP server, so any assistant that can add a custom connector by link can use it. Same link, same tools.
Add it to ChatGPT
- 1
Open ChatGPT settings
In ChatGPT, open Settings, then Connectors (called Apps & Connectors on some accounts).
- 2
Turn on developer mode
Under Advanced settings, switch on Developer mode. That is what lets you add a connector by link.
- 3
Create the connector
Choose Create, give it a name, paste the link as the MCP server URL, and save. If it needs a sign-in, ChatGPT asks for it here.
- 4
Use it in a chat
Start a chat, open the tools menu, pick the connector, and ask. ChatGPT asks before it runs a tool the first time.
Custom connectors need a paid ChatGPT plan, and on Team, Enterprise and Edu accounts only an admin can add them. Our "Working" label means the server answered us; it cannot tell whether your plan lets you add it. All connectors that work in ChatGPT
Add it to Claude
- 1
Open Claude settings
In Claude, open Settings, then Connectors.
- 2
Add a custom connector
Choose Add custom connector, give it a name, and paste the link.
- 3
Connect and use it
If it needs a sign-in, Claude sends you to it. Then turn the connector on in a chat from the tools menu and ask.
Custom connectors are available on paid Claude plans; on Team and Enterprise accounts an admin may need to add them. Our "Working" label means the server answered us; it cannot tell whether your plan lets you add it. All connectors that work in Claude
https://mailblaze.usefulapi.io/mcpWhat people ask Muse to do
Technical details: safety screening, tools, response time and recent checks
Response time at the last check: 189ms. Worked in n/a of checks over 30 days.
Screening · October 29, 2026
Screened, no issues found
Screening looks for known threats and hidden instructions at the time of the check, and runs again weekly and whenever the tool list changes. It cannot see the server's code, so only connect what you need and review what Muse asks to do. How screening works.
Tools · 26
mailblaze_list_listsList the account's mailing lists (name, uid, subscriber counts, defaults). Use the list uid in the other tools. Paged: page + per_page.mailblaze_get_listGet one mailing list by its uid: general settings, default sender, company details and counts.mailblaze_list_list_fieldsList 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_segmentsList the segments defined on a mailing list (uid, name). A segment uid can be used when creating a campaign.mailblaze_list_subscribersList the subscribers of a mailing list (sets of 10 per page; use page to go on). Contains personal data (emails, names).mailblaze_get_subscriberGet one subscriber of a list by subscriber uid (status, fields, dates).mailblaze_find_subscriber_by_emailLook up a subscriber in one list by email address. Returns the subscriber (with its uid) or a not-found error.mailblaze_add_subscriberWRITE, 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 mailblaze_add_subscribers_bulkWRITE, 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_subscriberWRITE: 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_subscriberWRITE: 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 rmailblaze_resubscribe_subscriberWRITE: 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_templatesList the account's email templates (uid, name). A template uid is needed to create a campaign.mailblaze_get_templateGet one email template by uid (name and content).mailblaze_create_templateWRITE: 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_campaignsList the account's email campaigns (uid, name, status, dates). Use the campaign uid for details and reports.mailblaze_get_campaignGet one campaign by uid: sender, subject, list, template, status and schedule.mailblaze_create_campaignWRITE, 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,mailblaze_get_campaign_summariesBulk 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_breakdownInbox-provider breakdown (e.g. Gmail, Outlook, Yahoo) of a campaign's delivery.mailblaze_list_campaign_eventsList 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_activityEmail activity (sends, opens, clicks, bounces) of one subscriber by email address, optionally limited to one list. Cursor-paged.mailblaze_get_report_jobStatus (and result when finished) of an asynchronous report job, as returned in a 202 reply with a job_id.mailblaze_list_transactional_emailsList the transactional emails sent through the account (uid, recipient, subject, status). Paged.mailblaze_get_transactional_emailGet one transactional email by uid: recipient, subject, status and timestamps.mailblaze_send_transactional_emailWRITE, 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 Link
https://mailblaze.usefulapi.io/mcpQuestions about Mail Blaze in Muse
How do I connect Mail Blaze to Muse?
Not in Muse's Connectors list yet, but Muse can still use it. Paste this into Muse: "Use Mail Blaze to help me. It is a free service with an MCP server at https://mailblaze.usefulapi.io/mcp. It does not need an API key. Ask me before you share anything with it." Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.
Is Mail Blaze working right now?
At the last check (October 29, 2026, 23:41 UTC) the endpoint was working, answering in 189ms. It is checked every 15 minutes.
Is Mail Blaze safe to connect to Muse?
It was screened on October 29, 2026 with the result "screened, no issues found". Screening checks the domain against threat feeds and reads the tools for hidden instructions and requests for passwords or card numbers. It cannot see the server's code, so grant only the access you need.
What can Mail Blaze do in Muse?
It exposes 26 tools, including mailblaze_list_lists, mailblaze_get_list, mailblaze_list_list_fields, mailblaze_list_segments. For example, you could ask Muse: "Send a welcome email campaign to new subscribers on my mailing list next Monday at 9am."
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