Email infrastructure engineered with agent safety gates and human approval holds
Shield your customer base and sender reputation from malicious prompt injection, infinite recursion loops, and unauthorized email dispatches by autonomous AI agents.
Drop into your application in under 60 seconds
Native typed interfaces with zero unnecessary dependencies. Built for standard fetch and modern edge runtimes.
{
"keyName": "customer-support-agent",
"policy": {
"allowedRecipientDomains": ["mycompany.com", "partner.io"],
"maxEmailsPerHour": 50,
"requireHumanApproval": true,
"blockExternalAttachmentUrls": true,
"emergencyKillSwitch": "active"
}
}Declarative JSON safety policy applied to agent API keys to prevent prompt injection data exfiltration.
Engineered for high deliverability and zero incident risk
Every layer from edge connection pooling to per-key rate limits is designed to keep critical transactional dispatches fast, reliable, and contained.
Prompt Injection Quarantine
Isolate outbound emails generated from untrusted inbound user inputs until safety checks pass.
Human-in-the-Loop Gatekeeper
Flag dispatches matching high-risk heuristics for manual human review in /app/approvals.
Velocity Tripwires
Hardware-enforced rate ceilings immediately halt dispatch if an agent attempts more sends than its configured burst limit.
Recipient Boundary Containment
Enforce per-key wildcards (e.g. *@trusted.org) so compromised LLMs cannot exfiltrate data to attacker mailboxes.
Automatic Content Sanitization
Detect and strip dangerous script tags and malformed HTML payloads before SMTP submission.
Real-Time Kill Switch
Disable an agent's email capabilities instantly via dashboard or REST API without revoking other service keys.
SadaSend vs Standard Email Providers (SendGrid / Resend)
Standard providers treat all API requests equally, offering no protection when an LLM is hijacked.
| Feature & Capability | SadaSend | Standard Email Providers (SendGrid / Resend) |
|---|---|---|
| Prompt Injection Exfiltration Shield | ||
| Per-Key Allowed Recipient Domains | ||
| Automated Velocity Tripwires | ||
| Human Approval Workflow (/app/approvals) | ||
| Content Safety Pre-Flight Scans | Basic spam filter | |
| Free Tier with Safety Controls | 6,000 / mo included | No agent controls |
Start with 3,000 emails every month at zero cost
No artificial paywalls on security. Unlike legacy providers that reserve recipient allowlists or dedicated IP pools for high enterprise tiers, every SadaSend account receives full safety controls from day one.
Everything you need to know about safe email for AI agents
Clear, transparent answers on deliverability, API authentication, and rate limits.
Related developer guides and architectural tutorials
Explore step-by-step production implementation blueprints, benchmarks, and protocols.
AI coding agent rules (AGENTS.md, Cursor, Claude)
Setup instructions and rule files for AI coding agents: AGENTS.md, .cursorrules, CLAUDE.md, and hosted MCP configuration.
REST API Reference & Endpoints
Complete REST API reference for sending emails, managing API keys, tracking delivery events, and configuring recipient allowlists with low latency.
Model Context Protocol (MCP) Server
Connect AI agents directly to SadaSend via Model Context Protocol (MCP). Inspect tools, configure execution scopes, and enable human approval holds.
Indirect Prompt Injection Defense in Email: Sanitizing Inbound Content for AI
Inbound emails processed by AI agents can contain hidden jailbreaks designed to hijack tools. Here is how to engineer a multi-layer prompt injection defense pipeline.
Indirect Prompt Injection via Email: Threat Models, Attack Vectors, and Prevention
When an AI agent reads incoming emails and holds a sending key, an attacker can embed invisible instructions. Here is how indirect prompt injection works and how to neutralize it.
How to Safely Let Agents Send Email: Defense-in-Depth for Autonomous Outbound
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Email Threat Modeling for SaaS: Preventing Compromised API Key Abuse
What happens when an engineer accidentally commits an email API key to a public GitHub repo? Here is the threat model and defense blueprint.