PostMTA Operator Documentation

Everything you need to configure, operate, and scale your email infrastructure with PostMTA. PostMTA is a managed MTA (Mail Transfer Agent) appliance with an API-first design — you send email by calling the REST API, and PostMTA handles deliverability, reputation, encryption, and analytics.

What Is PostMTA?

PostMTA is a credit-gated managed email sending platform. Instead of operating your own mail server infrastructure, you integrate with the PostMTA API and let PostMTA handle:

• MTA operations — SMTP relay, MX handling, retry logic, queue management
• TLS encryption — TLS 1.3 on all outbound connections, certificate management via Let's Encrypt
• Authentication — DKIM signing, SPF alignment, DMARC reporting
• Sender reputation — Per-domain and per-IP reputation tracking, IP warmup
• Analytics — Delivery, engagement, bounce, and complaint metrics
• Compliance — List-unsubscribe handling, spam testing, TLS reporting

Documentation Structure

The docs are organised into five groups:

Quick Start

API Base URL

https://api.postmta.com/v1

Send Your First Email

curl -X POST https://api.postmta.com/v1/messages/send \
  -H "Authorization: Bearer ***" \
  -H "Content-Type: application/json" \
  -d '{
    "from": {"address": "hello@yourdomain.com"},
    "to": [{"address": "recipient@example.com"}],
    "subject": "Welcome",
    "html": "<h1>Hello!</h1><p>Welcome to Example Co.</p>"
  }'

You should receive a 201 Created response with {'{'}'{'{'}'{'}'}'{'{'}'{'{'}'{'}'}'{'{'}'{'}'}'{'}'}"id": "msg_01HX...", "status": "queued"{'{'}'{'{'}'{'}'}'{'{'}'{'}'}'{'}'}'{'{'}'{'}'}'{'}'}. The email will be delivered within seconds.

Rate Limits by Plan

HTTP Status Codes

Official SDKs

Support and Status

• Email support: hello@netwit.ca
• Status page: https://status.postmta.com
• API OpenAPI spec: https://api.postmta.com/v1/openapi.json
• Community forum: https://community.postmta.com
• Changelog: PostMTA Changelog