How AI Agents Send Email: A Developer's Guide

One API call and your agent can send email

Most email APIs assume a human signs up in a browser, clicks a verification link, and creates a key from a dashboard — none of which an autonomous agent can do. AISend gives agents a fully programmatic path: one unauthenticated POST to /v1/auth/agent-signup returns a ready-to-use API key. No browser, no CAPTCHA, no email-verification loop.

curl -X POST https://api.aisend.app/api/v1/auth/agent-signup \
  -H "Content-Type: application/json" \
  -d '{"name": "support-bot"}'

# =>
# {
#   "token": "eyJhbGci...",        // JWT for dashboard/API calls
#   "apiKey": "re_live_...",        // use as Bearer on /api/v1/emails
#   "userId": "usr_...",
#   "email": "support-bot-a1b2c3@agent.aisend.app",
#   "expiresAt": "2027-..."
# }

The one gate that remains: a sending domain

The signup is frictionless, but sending to real recipients still requires a domain you've verified — the same reputation gate every reputable provider enforces, and deliberately so: it's what stops an agent account from being turned into a spam relay. The free plan includes one domain, so in practice you verify a domain once (one DNS step), then the agent sends against it indefinitely. Until then, the agent can send test emails to its own account address to confirm the integration works. Agent accounts start on the free tier at 3,000 emails/month.

Sending emails from Claude and GPT

If you're building with Claude's tool use or GPT's function calling, define a send_email function with parameters for recipient, subject, and body; when the LLM decides to send, your code executes the AISend API call. If your agent runs in an MCP client (Claude Desktop, Claude Code, Cursor), skip the glue entirely — the published aisend-mcp server exposes send_email and seven other tools natively (npm install -g aisend-mcp). One thing to be clear about scope: AISend is send-plus-MCP, not a mailbox. If your agent needs to receive, parse, and reply to email — a full two-way inbox per agent — that's a different kind of tool. AISend is the right fit when the agent needs to send: reports, alerts, summaries, notifications, outreach.

Security considerations for agent email

Giving an AI agent email capabilities requires careful guardrails. Rate-limit how many emails the agent can send per session. Validate recipient addresses against an allowlist if the agent serves a specific audience. Log every email the agent sends for audit purposes. Use AISend's webhook events to track delivery and flag any bounces or complaints. Never give the agent access to your primary sending domain — use a dedicated subdomain (e.g., agent.yourapp.com) so any reputation issues from agent-sent emails don't affect your main transactional email flow.

Building production agent email systems

For production deployments, wrap AISend in a thin service layer that enforces your business rules before the agent can send. This layer should validate the recipient is authorized, check the content doesn't contain sensitive data, enforce sending limits, and log the request. Use AISend's idempotency keys to prevent duplicate sends if the agent retries a failed request. Monitor agent email metrics separately from your application's transactional email — agent sending patterns differ from human-triggered patterns, and you want separate dashboards for each.