How to send cold email programmatically with an API

Developers reach for a transactional email API — Resend, Postmark, SendGrid — to send from their app. They are excellent at receipts, password resets, and notifications. But point one at cold outbound and you will hit a wall: their terms of service prohibit it, and they will suspend you.

Why transactional APIs say no

Transactional providers protect shared IP reputation fiercely. Cold email — unsolicited, higher-complaint — is the fastest way to poison that shared pool, so they ban it. That leaves a real gap: how do you send cold-adjacent outbound programmatically, without a UI-first agency tool?

The deliverability API approach

CogniLead fills that gap: a clean REST API for outbound that is built for cold-adjacent sending. You POST a send; it runs through suppression, dispatches over a warmed sender pool, and tracks delivery, bounces, and replies.

curl -X POST https://api.cognilead.ai/api/v1/sends \
  -H "Authorization: Bearer pk_live_..." \
  -H "Content-Type: application/json" \
  -d '{ "to": "lead@acme.com", "subject": "...", "body_md": "..." }'

What you get that a raw mail API lacks

• A managed warmed sender-domain pool — no buying and warming inboxes yourself.
• A reputation circuit-breaker that auto-pauses a domain on spam-rate drift.
• Suppression and RFC 8058 one-click unsubscribe honored on every send.
• Per-send pricing instead of a per-seat subscription.
• Jurisdiction-aware processing for data residency.

The full contract is in the API reference, and pricing is per send — see the pricing page.