SadaSend is the transactional email API with server-enforced safety ceilings, built for developers and engineering teams who need bulletproof guardrails against staging leaks and runaway AI agent loops.
Give your agent email.
Keep your peace of mind.
The transactional email API with server-enforced safety ceilings. Per-key recipient allowlists, human approval mode, and a native hosted MCP server—so an autonomous agent or staging test can never leak to real customers.
3,000 emails free · no card · every guardrail on every plan
// The ceiling, set once when the key is minted.
// The agent gets the key. It cannot widen any of this.
{
scopes: ['send', 'read'], // what it may do
allowlist: ['@yourteam.com'], // who it may reach
rateLimitMax: 50, // how fast
rateLimitWindow: '1h',
mode: 'approval', // who signs off
}Inbox placement enforced by architecture, not luck
Mailbox providers (Gmail, Yahoo, Apple, Microsoft) immediately drop non-compliant traffic. SadaSend enforces RFC 8058 one-click unsubscribe, strict SPF/DKIM/DMARC alignment, and sub-0.10% complaint throttles directly at the gateway before packets leave.
- SPF · DKIM · DMARC
- Cryptographically verified before your first production packet leaves
- RFC 8058 Unsubscribe
- Machine-readable one-click unsubscribe headers injected automatically
- Complaint Guard
- Watched per account in real time, throttled before reaching 0.10%
- Instant Suppression
- Hard bounces and complaints automatically suppressed account-wide
Traditional email APIs grant binary access. SadaSend enforces architectural safety ceilings.
Handing an AI agent a standard bearer token gives it carte blanche to email anyone in the world until credits run dry. SadaSend enforces immutable safety gates at the API edge—allowlists, execution scopes, rate limits, and approval holds—included on every plan.
keys.createEnforced at the API before the send reaches the queue — not in a doc, not in a lint rule, and not dependent on the agent behaving.
How SadaSend guarantees zero runaway email
The barrier sits in front of the queue, not in a help doc or an agent prompt. Every send is validated at the edge before anything is dispatched.
Agent initiates tool call
Your agent (Claude, Cursor, LangChain) invokes send_email with recipient and body. It cannot alter the key’s preset limits.
SadaSend evaluates policy gate
Every send is verified against the key’s immutable scopes, recipient allowlist, hourly rate limits, and suppression history.
Instant dispatch or human sign-off
Allowlisted transactional sends are accepted and queued immediately. Out-of-allowlist sends are refused; high-risk sends hold in pending_approval for 1-click human clearance.
- Zero LLM Training
- Customer email content, variables, and payloads are never used to train or fine-tune models.
- Immutable Scopes
- Agents hold keys that can only send or read — never mint keys, delete domains, or remove suppressions.
- Cryptographic Webhooks
- HMAC-SHA256 signatures with timestamp replay protection on all delivery events.
- Immutable Audit Trail
- Every attempt, refusal, and delivery event is logged with microsecond timestamps for forensic review.
Under ten lines to a delivered email
Install, set a key, send. Zero-dependency official TypeScript and Python SDKs live on npm and PyPI, alongside our hosted Model Context Protocol (MCP) server for AI agents.
https://mcp.sadasend.com/sse// Universal Model Context Protocol (MCP) Server for AI Agents
// Native integration for Antigravity, Cursor, Cline, Windsurf & Claude
{
"mcpServers": {
"sadasend": {
"url": "https://mcp.sadasend.com/sse",
"headers": {
"Authorization": "Bearer $SADASEND_API_KEY"
}
}
}
}
// 10 email tools: send_email, send_batch, check_domain_dns, verify_domain, etc.Looking for full API schemas, error codes, webhook verifiers, or MCP tools?
Explore all documentationConnects with the tools your team already builds with
Whether you dispatch from visual automation platforms, full-stack BaaS databases, internal ops dashboards, or autonomous AI agents, SadaSend connects seamlessly via standard SMTP (port 587), a low-latency REST API, or a native Model Context Protocol (MCP) server.
Automate transactional notifications and customer alerts in n8n workflows with zero SMTP socket timeouts or Gmail rate limits.
Bypass the default 2/hour email limit. Connect SadaSend custom SMTP to deliver unthrottled magic links and verification emails.
Fix broken sendmail in production. Configure SadaSend in the PocketBase Admin UI or trigger custom alerts with Go and JS hooks.
Trigger transactional emails and password resets directly from internal admin panels with your own verified, white-label domain.
Plug SadaSend into visual scenarios using the HTTP request module. High throughput, zero account freeze risks, and webhook sync.
Equip visual AI agents with email sending tools while enforcing scoped keys, recipient allowlists, and human approval mode.
Render beautiful, responsive React Email components server-side and dispatch via Server Actions with zero external SMTP dependencies.
First-party hosted Model Context Protocol server. Agents can compose, preview, and send emails with hardware-grade safety ceilings.
A hosted MCP server with an architectural ceiling
Connect Claude, Cursor, Windsurf, or custom AI agents in one command. Your agent gets ten safe tools to compose, preview, and monitor email — with zero access to credential generation, domain deletion, or suppression tampering.
claude mcp add --transport http sadasend https://mcp.sadasend.com| Tool | Scope | Does |
|---|---|---|
| send_email | send | Send one, honouring key mode and allowlist |
| preview_email | send | Dry run — render and validate, never send |
| get_email_status | read | Delivery state and full event trail |
| search_emails | read | Filtered log search — the debugging workhorse |
| list_domains | read | Which domains are verified — the first check when a send is refused |
| check_domain_setup | domains | Per-record DNS diagnosis, with the fix |
| list_templates | read | Templates on the account, with the variables each expects |
| check_suppression | read | Is this address suppressed, and why |
| render_template | read | Preview a template without sending |
| get_stats | read | Bounce and complaint rates for a window |
| inspect_allowlist | read | Active key recipient allowlist and approval mode |
| get_key_quota | read | Rate limit usage, remaining sends, and reset time |
There is no create_api_key, no delete_domain, and no remove_suppression tool. An agent that can mint its own credentials or un-suppress a complainer has no ceiling. Those operations live exclusively in the dashboard under authenticated human control.
- “Send the welcome email to the three users who signed up this morning.”
- “Why did our password reset to dana@example.com bounce yesterday?”
- “Check whether our DNS is set up correctly for sending.”
- “Show me every email that bounced this week, grouped by reason.”
Ready to connect Antigravity, Cursor, Windsurf, or Claude Desktop?
Deliverability tools that tell you the fix
We are building these on the same verification engine that onboards sending domains. Free, no account, no rate limit, no email capture — launching soon.
- SPF checkerNewResolves every include and counts your lookups against the limit of ten.
- DKIM validatorNewFetches the selector, checks the key length, verifies a signature.
- DMARC checkerNewParses your policy and tells you what it actually does to failing mail.
- MX lookupNewResolves the chain and flags misconfigurations.
- Blocklist checkNewQueries the major blocklists for an IP or domain.
- Inbox placement testNewSend one message and see where it lands across major providers.
- Disposable email checkerNewDetects temporary, throwaway burner addresses before they bounce.
Where we excel, and where others focus
Every row in our column is a capability you can check against the API today, not a roadmap. If you need a drag-and-drop newsletter builder for marketing campaigns, traditional visual campaign tools are designed for that. But if you need bulletproof transactional infrastructure, hardware-grade AI agent allowlists, and a hosted MCP server with an architectural ceiling, choose SadaSend.
| Capability | SadaSend | Resend | Postmark | Loops |
|---|---|---|---|---|
| Transactional email API | Yes | Yes | Yes | Yes |
| MCP server | Yes | Yes | Partial | Yes |
| Per-key recipient allowlist | Yes | No | No | No |
| Agent approval mode | Yes | No | No | No |
| Dry run / preview send | Yes | Partial | No | No |
| Scoped API keys | Yes | Partial | Partial | Partial |
| Per-key rate limit | Yes | Partial | Partial | Partial |
| SMTP relay | Yes | Yes | Yes | No |
| Free deliverability tools | Yes | No | Partial | No |
| Marketing campaign suite | No | Yes | No | Yes |
| Visual email designer | No | Yes | No | Yes |
Enterprise-grade safety on an indie budget
Every guardrail and all ten MCP tools are included on every tier, including the free plan. We do not gate safety behind expensive enterprise sales calls or lock dedicated IPs behind $89.95/month surcharges.
- 6,000 emails a month — every month, no card
- 200 emails / day burst limit
- 3 sending domains
- 30-day log & body retention
- All ten MCP tools
- Every guardrail & allowlist
- 15,000 emails / month
- No daily limit (burst exempt)
- 6 sending domains
- 30-day log retention
- SMTP relay & REST API
- Free migration assistance
- 75,000 emails / month
- 25 sending domains
- 60 days message & log retention
- 10 webhook endpoints
- Webhook replay & dead-letter sync
- Per-attempt delivery logs
- 250,000 emails / month
- Unlimited sending domains
- 90-day log retention
- 25 webhook endpoints
- Priority sending queue
- Priority developer support
Start on the free plan without a credit card. Yearly billing saves 15% on Starter and Pro, 20% on Scale. Transparent overage: $0.60, $0.50, or $0.40 per thousand emails by plan, billed only for what you send. Zero per-seat charges, ever.
Straight answers
Each answer stands on its own, so you can quote it without the rest of the page.
Stop worrying about runaway email. Ship today.
Generate a scoped API key, set your recipient allowlist, and point your agent or backend at SadaSend. 6,000 emails free forever with zero credit card required.
- 6,000 emails free forever
- All 10 MCP tools included
- Every guardrail active on Day 1
- No credit card required