Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type @ followed by the MCP server name and your instructions, e.g., "@send16-mcp Send a test email from onboarding@send16.com to my account with subject 'It works'."
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
The email API your AI agent can actually use. A Model Context Protocol server for Send16 that gives Claude, Cursor, and any MCP client 79 tools to send transactional & marketing email, manage contacts, audiences, segments, automations, templates, the inbox, suppressions, and webhooks — from natural language.
It ships a zero-DNS sandbox sender, so an agent can send its first real, delivered email in seconds with no domain setup.
npx send16-mcpYou need a Send16 API key (sk_live_…) from your dashboard. Then pick your client:
claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\):
{
"mcpServers": {
"send16": {
"command": "npx",
"args": ["-y", "send16-mcp"],
"env": { "SEND16_API_KEY": "sk_live_..." }
}
}
}.cursor/mcp.json:
{
"mcpServers": {
"send16": {
"command": "npx",
"args": ["-y", "send16-mcp"],
"env": { "SEND16_API_KEY": "sk_live_..." }
}
}
}Windsurf, VS Code, and any stdio-capable MCP client work the same way — run the send16-mcp binary with SEND16_API_KEY in the environment.
For clients that only speak remote MCP (Claude web connectors, ChatGPT custom GPTs), point them at the hosted endpoint and authenticate with your key:
https://mcp.send16.comOne connection, your own sk_live_… key — no install, no config file.
Related MCP server: sendook-mcp
Most email APIs make you verify a domain before you can send anything, which blocks an unattended agent on step one. Send16's sandbox sender doesn't:
Ask the agent to call whoami — it returns your workspace and your sandbox_recipient (your account owner's email).
Send from: "onboarding@send16.com" to that address. It delivers with zero DNS setup.
Verify a domain later to send to anyone.
"Send a test email from onboarding@send16.com to my account email with the subject 'It works'."
79 tools across the platform, including:
Email — send_email (single/batch/scheduled/attachments), transactional templates, delivery status.
Marketing — campaigns, broadcasts, automations, segments, subscription topics.
Contacts — create/search/list/import, audiences, tags, custom fields.
Deliverability — domains, DNS health (SPF/DKIM/DMARC), IP warming & sending capacity.
Inbox — read and manage transactional replies.
Webhooks — create/list/rotate outgoing webhook endpoints (HMAC-SHA256 signed).
Every tool also accepts an optional apiKey parameter that overrides SEND16_API_KEY, so you can switch workspaces in one session.
Variable | Required | Description |
| Yes | Your Send16 key ( |
| No | API base URL (default: |
| No | If set, serves Streamable HTTP (multi-tenant) instead of stdio |
Presence of SEND16_MCP_PORT flips the server into multi-tenant HTTP mode — each request carries its own Authorization: Bearer sk_live_…, threaded through the whole request, so one process serves many users:
docker build -t send16-mcp . && docker run -p 4242:4242 send16-mcpnpm install
SEND16_API_KEY=sk_live_... npm run dev # run from source
npm run build # bundle to dist/Site & docs: https://send16.com · https://send16.com/docs
Status: https://status.send16.com
MIT © Spruik Co
Activate an automation. New events matching its triggers will start enrolling contacts.
Inputs: automationId (required), apiKey.
Add contacts (by ID) to an audience.
Inputs: audienceId (required), contactIds (required), apiKey.
Add a private internal note on a conversation. Notes are visible only to workspace members.
Inputs: body (required), convoId (required), apiKey.
Register a new sending domain. Returns the DNS records the user must add to their DNS provider, after which they should call check_domain_health to verify.
Inputs: domain (required), apiKey.
Add an email to the suppression list. Future sends to this address will be blocked.
Inputs: email (required), notes, apiKey, reason.
Check the DNS health of a specific domain, including DKIM, SPF, DMARC, and MX record verification status. Triggers a fresh DNS lookup.
Inputs: domainId (required), apiKey.
Create an Action that maps an event name to a transactional template. Each matching event sends one email to the contact.
Inputs: name (required), eventName (required), templateSlug (required), apiKey, +3 more.
Create a new audience.
Inputs: name (required), apiKey, description.
Create a new email campaign in Send16. The campaign is created in draft status and can be edited before sending.
Inputs: name (required), subject (required), fromName (required), fromEmail (required), +3 more.
Add a new contact to your Send16 audience. Contacts are automatically subscribed to receive emails.
Inputs: email (required), tags, apiKey, lastName, +2 more.
Create a new subscription topic. Contacts opt into topics individually via the preference center.
Inputs: name (required), slug, apiKey, isDefault, +1 more.
Register an outgoing webhook endpoint. Send16 POSTs event JSON to this URL with an HMAC-SHA256 signature. Outgoing webhooks are a plan feature.
Inputs: url (required), name (required), events (required), apiKey, +1 more.
Delete an Action.
Inputs: actionId (required), apiKey.
Delete an audience (list). Contacts are not deleted — only the list and its memberships are removed.
Inputs: audienceId (required), apiKey.
Delete a draft campaign. Sent campaigns cannot be deleted (only archived).
Inputs: campaignId (required), apiKey.
Delete a contact and all associated events. Irreversible.
Inputs: contactId (required), apiKey.
Delete a subscription topic. All subscribers will be detached.
Inputs: topicId (required), apiKey.
Delete an outgoing webhook endpoint.
Inputs: webhookId (required), apiKey.
Use AI to generate a complete email HTML template based on a description. Returns ready-to-use HTML that can be sent or used in campaigns.
Inputs: type (required), style (required), description (required), apiKey, +2 more.
Duplicate a campaign as a new draft. Useful for A/B variants or re-using a successful template.
Inputs: campaignId (required), apiKey.
Manually enroll a contact in an active automation. The automation must be in 'active' status. Use send_event for event-driven enrollment.
Inputs: contactId (required), automationId (required), apiKey.
Scrape a URL (e.g. a launch blog post or product page) and generate an email draft from its content. Returns subject, preview text, and HTML body.
Inputs: url (required), apiKey, instructions.
Get a single Action with its trigger config and template binding.
Inputs: actionId (required), apiKey.
Get a single automation by ID, including its trigger, steps, and current status.
Inputs: automationId (required), apiKey.
Get aggregate analytics for an automation: total enrollments, completed, exited, open/click rates per step.
Inputs: automationId (required), apiKey.
Get the workspace's brand settings: colors, logo, fonts, and the DESIGN.md spec injected into AI generation prompts.
Inputs: apiKey.
Get detailed performance statistics for a specific campaign including open rate, click rate, bounce rate, and delivery metrics.
Inputs: campaignId (required), apiKey.
Get a contact's 0-100 health score based on recent engagement (opens, clicks, replies).
Inputs: contactId (required), apiKey.
Get a contact's full activity timeline: emails received, events fired, opens, clicks, automation enrollments, topic changes.
Inputs: contactId (required), limit, apiKey, cursor.
Get a single conversation with its full thread of posts (incoming + outgoing).
Inputs: id (required), apiKey.
Get your workspace's deliverability summary — sending reputation, domain authentication status, and recent bounce/complaint health. (Deliverability Hub plan feature.)
Inputs: apiKey.
Fetch a single message with its full event timeline (created → sent → delivered → opened → clicked → ...).
Inputs: id (required), apiKey.
Get just the delivery event timeline for a message — no body or recipient details.
Inputs: id (required), apiKey.
Get a single starter template by ID, including its EmailContent JSON.
Inputs: templateId (required), apiKey.
Get the current workspace (the one the API key belongs to).
Inputs: apiKey.
Get the current month's send count, contact count, and plan limits.
Inputs: apiKey.
Bulk import contacts from CSV data. Each row should have at minimum an email column. Tags can be applied to all imported contacts.
Inputs: csvData (required), tags, apiKey, updateExisting.
List Actions. Actions fire a transactional template when a custom event arrives — Plunk-style 'event_name → template' pairings, simpler than full automations.
Inputs: apiKey.
List audiences (lists). An audience is a static, manually-managed group of contacts.
Inputs: apiKey.
List active and historical enrollments for an automation.
Inputs: automationId (required), limit, state, apiKey, +1 more.
List all automations in the workspace, including draft/active/paused status and trigger types.
Inputs: apiKey.
List email campaigns with optional status filtering and pagination.
Inputs: page, apiKey, status, pageSize.
List all contacts with optional filtering by subscription status and tag. Supports pagination.
Inputs: page, tagId, apiKey, pageSize, +1 more.
List inbox conversations. Filter by state, mailbox, label, screener status, or full-text search. Send16's unified inbox combines transactional reply threading with team-managed shared inboxes.
Inputs: label, limit, state, apiKey, +4 more.
List all sending domains configured in your Send16 workspace, including their verification status and DNS records.
Inputs: apiKey.
Get unread/total counts per category and label for the inbox sidebar (newsletter, transactional, marketing, calendar, social, cold).
Inputs: apiKey.
List messages from the unified send log (transactional + campaign). Filter by recipient, sender, status, date range, or source.
Inputs: limit, apiKey, offset, source, +5 more.
List dynamic segments. Segments compute their members from a filter expression at send time.
Inputs: apiKey.
List suppressed email addresses (bounces, complaints, unsubscribes, manual).
Inputs: limit, apiKey, offset, reason.
List starter-gallery email templates available to every workspace.
Inputs: apiKey.
List subscription topics. Topics are granular categories contacts can subscribe to (e.g. 'product-updates', 'weekly-digest'). Campaigns and automations can be gated to subscribers of a specific topic.
Inputs: apiKey.
List configured outgoing webhooks (your endpoints that Send16 POSTs delivery events to). Outgoing webhooks are a plan feature.
Inputs: apiKey.
List workspaces the authenticated user has access to (owner or member).
Inputs: apiKey.
Mark a conversation as read for the current viewer.
Inputs: convoId (required), apiKey.
Pause an automation. Existing enrollments freeze in place; no new contacts enroll.
Inputs: automationId (required), apiKey.
Pause a sending campaign. Already-sent messages are unaffected; remaining sends halt.
Inputs: campaignId (required), apiKey.
Run an AI pre-send review on an email's HTML before sending. Surfaces tone issues, broken links, missing alt text, spam triggers, and accessibility problems.
Inputs: html (required), subject (required), apiKey, audience.
Preview the recipient set for a campaign before sending. Returns count + sample list.
Inputs: campaignId (required), apiKey.
Preview the contacts that match a segment without sending.
Inputs: segmentId (required), apiKey.
Rotate the HMAC signing secret for an outgoing webhook endpoint. Returns the new secret once.
Inputs: webhookId (required), apiKey.
Remove a contact from an audience.
Inputs: contactId (required), audienceId (required), apiKey.
Remove an email from the suppression list. Use only when you've confirmed the recipient wants to receive mail again.
Inputs: email (required), apiKey.
Compile an EmailContent JSON object (the shape used by the Send16 builder + templates) into HTML using the platform's authoritative renderer. Returns the exact HTML the API would send. Useful for previews and post-processing.
Inputs: content (required), apiKey, variables.
Resume a paused campaign.
Inputs: campaignId (required), apiKey.
Schedule (or send immediately) an existing draft campaign to an audience/segment/topic.
Inputs: campaignId (required), apiKey, topicId, segmentId, +2 more.
Decide a pending screener conversation (first-time sender). 'allow' lets future emails through, 'reject' blocks, 'cold' marks as cold outreach.
Inputs: convoId (required), decision (required), apiKey.
Search contacts by email address or name. Returns matching contacts with their tags and subscription status.
Inputs: query (required), page, apiKey, pageSize.
One-shot broadcast: create a campaign and immediately schedule it to send. Mirrors Resend's one-call broadcast API. Pass either an audienceId, segmentId, topicId, or fully-qualified filter. Provide html OR templateSlug.
Inputs: name (required), subject (required), fromName (required), fromEmail (required), +9 more.
Send a test email for an existing campaign to preview how it will look in recipients' inboxes.
Inputs: testEmail (required), campaignId (required), apiKey.
Send a transactional email through Send16. Provide html, text, or both (text-only is fine for OTPs/receipts/alerts). from_email must belong to a domain that is verified in the workspace — call whoami for the account and list_domains to see which senders are allowed; a send from an unverified domain returns a clear error, not a silent failure. For a zero-setup first send, use from_email onboarding@send16.com — the sandbox sender delivers with no DNS, but only to your own account email.
Inputs: to (required), subject (required), html, text, +6 more.
Fire a custom event for a contact. Automations whose trigger is {type:'custom_event', eventName:'<name>'} will enroll the contact and start running. Payload is exposed to condition steps as event.<key>.
Inputs: name (required), apiKey, payload, contactId, +2 more.
Reply to an inbox conversation. The reply is sent from the original recipient address (the alias the convo arrived on) and threaded back to the contact.
Inputs: convoId (required), html, text, apiKey.
Update an Action (toggle enabled, change template, change event name).
Inputs: actionId (required), name, apiKey, enabled, +4 more.
Update workspace brand settings. The designSpec field is a Markdown DESIGN.md document fed into AI generation system prompts — use it to encode voice, do/don't lists, and visual rules.
Inputs: apiKey, logoUrl, designSpec, fontFamily, +2 more.
Update a draft campaign's content, subject, preview text, or sender info.
Inputs: campaignId (required), html, apiKey, replyTo, +5 more.
Update a contact's profile fields, custom fields, or subscription state.
Inputs: contactId (required), apiKey, lastName, firstName, +2 more.
Update conversation state (open/closed/snoozed/spam/trash), star, or assignee.
Inputs: convoId (required), state, apiKey, starred, +1 more.
Update a subscription topic (name, description, default).
Inputs: topicId (required), name, apiKey, isDefault, +1 more.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
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Scored across 79 tools
Many tools exist for overlapping concepts (e.g., send_email, send_broadcast, send_campaign_test, send_reply; create_campaign vs schedule_campaign vs send_broadcast). While descriptions help, the large number of tools increases the chance of selecting the wrong one for a task.
All tool names follow a consistent verb_noun pattern in snake_case (e.g., activate_automation, add_contacts_to_audience, send_event). No mixing of conventions like camelCase, making it predictable for an agent.
With 79 tools, this server is well beyond the recommended range. While it aims to cover a full email marketing platform, the sheer number makes it unwieldy and suggests it could be split into multiple focused servers.
The tool surface covers most major workflows (sending, contacts, campaigns, automations, analytics). However, notable gaps exist: no tools to create or update segments or email templates (only list/get), and no tag management tools.
Hosted email for AI agents: create inboxes, send, receive, and reply over MCP with scoped API keys
Email infrastructure for AI agents — send, receive, search, and reply to email over MCP.
Connect AI agents to Emitd email sending, message tracking, templates, and automations. Emitd hosts a Model Context Protocol server for integrating supported email operations into AI-agent workflows. Connect a compatible client to the hosted endpoint (https://mcp.emitd.com/mcp) and authenticate with an Emitd API key. Available tools depend on the key's permissions and enabled features. Emitd's capability areas include sending email, message activity, templates, contacts, audiences, segments, domains, analytics, inbound email, broadcasts, automations, webhooks, and suppressions. Use restricted keys, sending guardrails, and approval settings appropriate to each workflow. For more information check https://emitd.com
AgentiSend is a transactional email API: send through verified domains with a message log, budgets, a preflight and refusals that name the fix; built so AI agents can send on your behalf. The hosted MCP server at https://api.agentisend.com/mcp exposes 82 tools (44 on tools/list; the rest via list_more_tools). A send is one message or a batch of up to 500 items with per-item results. preflight_email runs every gate a real send runs, sends nothing, and costs nothing. Every 4xx returns code, message, and fix. There is no tool for unsolicited mail. Auth is a bearer API key or OAuth 2.1 with dynamic client registration. Starter prompts: "Send this receipt to the customer." "Preflight this send and tell me what would stop it." "What can I spend today?"
