AI Agents Accessible APIsEmail, team chat and notifications

Email, team chat and notifications APIs and MCP servers for AI agents

Send and receive email, post to team chat (Slack, Discord), send push notifications; manage meetings.

10 email, team chat and notifications APIs an AI agent can call: auth method and header, official MCP server (6), free tier (9), docs links. Machine-readable JSON included. Agents: fetch catalog/communication-email-chat.json instead of parsing this page. Last checked 2026-09-24.

Ratings and usage (★) fetched: .

ServiceWhat an agent can doAuthMCP serverFree tierDetails (with sources)NotesProof (ratings, usage)
AgentMailProgrammatically create inboxes and send/receive email autonomously, purpose-built for AI agents.API key
Authorization: Bearer <api_key>		officialFree: 3 inboxes, 3,000 emails/month (max 100/day), 3GB storage, no card requiredBase URL: https://api.agentmail.to/v0
Free plan: 3 inboxes, 3,000 emails/month (max 100/day), 3 GB storage, no card ↗
Rate limits: Per-organization API limits (unpublished); 429 with Retry-After on excess. Free plan capped at 100 emails/day ↗
Example call: send an email from an inbox: POST https://api.agentmail.to/v0/inboxes/{inbox_id}/messages/send ↗		Newer, smaller vendor than legacy ESPs; markets itself specifically as agent-native email infra with a built-in MCP server.—
Discord APISend messages, manage channels/roles, and build interactive bots via REST and Gateway API.API key / OAuth
Authorization: Bot <token> (OAuth2 Bearer only for user-authorized access and adding the bot to servers)		communityfree, no key needed beyond creating a bot applicationBase URL: https://discord.com/api/v10
Free plan: free_tier, no card ↗
Rate limits: Global 50 requests/s per bot plus per-route limits; 10,000 invalid requests per 10 min triggers IP ban ↗
OAuth scopes: bot, applications.commands ↗
Example call: send a message to a channel: POST https://discord.com/api/v10/channels/{channel.id}/messages ↗
MCP tools: 10: get_server_info, send_message, read_messages, edit_message, delete_message, send_private_message … ↗		Per-route rate limits; bots in 100+ servers require Discord verification/approval.GitHub 507★ SaseQ/discord-mcp
Smithery 82 uses
MailgunSend and validate transactional email via REST API and SMTP relay with webhooks.API key
Basic auth: api:<API_KEY>		officialfree: 100 emails/day; 30-day free trial on paid tiersBase URL: https://api.mailgun.net
Free plan: 100 emails/day, 1 custom sending domain, 1-day log retention ↗
Rate limits: Per-API time windows; X-RateLimit-* headers and 429 when exceeded. EU region host: api.eu.mailgun.net ↗
Example call: send an email: POST https://api.mailgun.net/v3/{domain_name}/messages ↗
Unit price: Overage from $1.80 per 1,000 emails (Basic, $15/mo incl. 10,000) or from $1.30 per 1,000 (Foundation, $35/mo incl. 50,000) ↗		Free plan limited to 1 sending domain and 1-day log retention. Official MCP server is local only (npx @mailgun/mcp-server, stdio).SourceForge 1.0★/1 review
ntfy.sh Push Notifications APILets an agent send push notifications to a user's phone or desktop by publishing a plain HTTP POST to an ntfy topic, and read messages back from it.none
No key for public topics: POST the message body to https://ntfy.sh/<topic>. Optional access token for reserved topics: 'Authorization: Bearer tk_<TOKEN>'		communityNo key; anonymous publishing to public topics, rate-limited per visitor IP (burst of 60 requests, then 1 request every 5 s, roughly 17,280/day); paid plans from $6/month add reserved topics, higher limits, email and phone-call notifications.Base URL: https://ntfy.sh
Free plan: Burst of 60 requests, then 1 request every 5 s per visitor, no card ↗
Rate limits: Defaults: burst 60 requests, replenish 1 request/5 s; attachments 100 MB total, 500 MB/day bandwidth per visitor ↗
Example call: publish a push notification to a topic: POST https://ntfy.sh/{topic} ↗
MCP tools: 2: ntfy_me, ntfy_me_fetch ↗		Public topic names act as passwords; anyone who knows the name can read or post, so use a hard-to-guess name or a reserved topic. Attachments up to 15 MB. Server is open source and self-hostable with the same API.—
PostmarkSend transactional email via REST API with delivery tracking, bounce handling, and templates.API key
X-Postmark-Server-Token: <token>		officialfree: 100 emails/month (Developer plan, no expiry)Base URL: https://api.postmarkapp.com
Free plan: 100 emails/month (Developer plan, no expiry), no card ↗
Rate limits: Unpublished acceptable-use limit; HTTP 429 when exceeded ↗
Example call: send one email: POST https://api.postmarkapp.com/email ↗
Unit price: overage per 1,000 emails: $1.80 (Basic), $1.30 (Pro), $1.20 (Platform); plans from $15/mo for 10,000 emails ↗
MCP tools: 24: sendEmail, sendEmailWithTemplate, sendBatch, sendBatchWithTemplate, listTemplates, getTemplate … ↗		Strictly transactional-email focused; enforces anti-bulk/anti-spam policy which can suspend accounts sending bulk/marketing mail. Official MCP server is local (npx @activecampaign/postmark-mcp).—
ResendSend transactional and marketing email via REST API with templates, domains, and webhooks.API key
Authorization: Bearer re_xxxxxxxxx		officialfree tier: 3,000 emails/mo, 100/dayBase URL: https://api.resend.com
Free plan: 3,000 emails/month (max 100/day), 3 domains ↗
Rate limits: 10 requests/s per team across all API keys ↗
Example call: send an email: POST https://api.resend.com/emails ↗
Unit price: Free: 3,000 emails/month (100/day); Pro $20/mo for 50,000 emails, then $0.90 per 1,000 extra emails ↗		Official remote MCP server at mcp.resend.com/mcp; sandbox domain available for testing before custom domain verification.SourceForge 4.0★/1 review
SendGrid (Twilio)Send transactional and marketing email via REST/SMTP API with templates and analytics.API key
Authorization: Bearer SG.xxxxxxxxx		—Trial: 100 emails/day for 60 days, no card required; paid plan afterBase URL: https://api.sendgrid.com/v3
Free plan: 100 emails/day for 60 days, no card ↗
Rate limits: Per-endpoint limits reported in X-RateLimit-* headers; HTTP 429 when exceeded ↗
Example call: send an email: POST https://api.sendgrid.com/v3/mail/send ↗
Unit price: Plans from $19.95/month (Essentials 50K emails); overage $0.0013 per email on 50K plan, $0.0009 on 100K plan, $0.0011-$0.0005 on Pro tiers ↗
MCP tools: 10: send_email, send_to_list, list_contacts, add_contact, list_contact_lists, create_template … ↗		Now a Twilio product; sender identity/domain authentication required before sending.SourceForge 3.9★/8 reviews
Slack APIPost messages, manage channels, and read conversation history in Slack via the Web API.OAuth 2.0
Authorization: Bearer xoxb-...		officialfree, no key needed beyond creating a Slack app/workspaceBase URL: https://slack.com/api
Free plan: free_tier, no card ↗
Rate limits: Per-method tiers: T1 1+/min, T2 20+/min, T3 50+/min, T4 100+/min; chat.postMessage ~1 msg/s per channel; non-Marketplace apps: conversations.history 1/min ↗
OAuth scopes: chat:write, channels:read, channels:history, groups:history, im:history ↗
Example call: post a message to a channel: POST https://slack.com/api/chat.postMessage ↗		Requires creating a Slack app with OAuth scopes; per-method rate-limit tiers apply. The official remote MCP (OAuth 2.0) works only for directory-published or internal Slack apps, and in partner clients such as Claude.Smithery 12.1k uses
SourceForge 4.6★/250 reviews
Stream (GetStream) Chat & Video APIBuild and moderate in-app chat and video with REST/SDK APIs, channels, and real-time messaging.API key
API key + server-side secret used to mint short-lived user JWT tokens		—Free tier: Build plan with 1,000 MAU/month and 100 concurrent connections, no card; Maker account gives $100/month credit for teams under 5 people and under $10k monthly revenueFree plan: Build plan: 1,000 MAU, 100 concurrent connections, per month, no card ↗
Rate limits: Per-endpoint per-minute limits (60 to 10,000/min, e.g. Send Message 1,000/min) plus 60 requests/min per user ↗
Example call: send a message to a channel (server-side): POST https://chat.stream-io-api.com/channels/{type}/{id}/message?api_key={API_KEY} ↗
Unit price: Chat overage: $0.09 per MAU above plan limit, $0.99 per extra concurrent connection, $5.00 per 1M stored messages ↗		Client access requires server-minted short-lived user tokens; not a pure send-and-forget messaging API like email/SMS providers.—
Zoom APISchedule, update, and manage meetings, webinars, and cloud recordings programmatically via REST API.OAuth 2.0
Authorization: Bearer <access_token> (Server-to-Server OAuth recommended for agents)		officialusable on free Zoom account within Basic plan limits; some endpoints require paid planBase URL: https://api.zoom.us/v2
Free plan: Free plan API limits: light 4/s and 6,000/day, medium 2/s and 2,000/day, heavy 1/s and 1,000/day, no card ↗
Rate limits: Per plan: Free light 4/s (6,000/day), Pro light 30/s, Business+ light 80/s; medium/heavy lower; 429 on excess ↗
Example call: create a scheduled meeting: POST https://api.zoom.us/v2/users/{userId}/meetings ↗		Server-to-Server OAuth app type is the recommended path for unattended agent use; some features gated behind licensed/paid plans. Official remote MCP servers (streamable HTTP, user OAuth) run at the mcp.zoom.us gateway.—

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