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Introduction

RelayPost is a developer-first email delivery platform. It handles transactional emails (password resets, receipts, alerts) and marketing campaigns (newsletters, broadcasts) through a single API.

  • REST API — send emails, manage templates, track delivery through standard HTTP endpoints
  • SMTP relay — drop-in replacement for any app that speaks SMTP
  • Domain authentication — automated DKIM key generation and DNS verification
  • Real-time tracking — delivery, open, bounce, and complaint events via webhooks
  • Suppression management — automatic bounce handling and manual suppression lists
  • Template engine — reusable email templates with variable substitution
  • Campaign builder — contact lists, segments, and broadcast sends
Your App → RelayPost API (or SMTP) → Email Queue → Delivery Engine → Recipient Inbox
Webhook Events → Your App
  1. You send an email via the API or SMTP
  2. RelayPost validates, queues, and delivers it
  3. Delivery events (delivered, bounced, opened) are sent to your webhook URL in real time

RelayPost uses two authentication methods:

MethodUse case
API KeyProgrammatic access via the REST API
SMTP CredentialsUsername/password for SMTP relay connections

Both are scoped to your organization and managed from the dashboard.

Quickstart — send your first email in 5 minutes