Introduction
What Is Transactional Email?
Section titled “What Is Transactional Email?”Transactional email is an automated message sent to a single recipient in response to a specific action, such as a password reset, order confirmation, or account verification. Unlike marketing email sent in bulk, transactional email is triggered by user behavior and typically achieves open rates above 80%.
What Is RelayPost?
Section titled “What Is RelayPost?”RelayPost is a developer-first email delivery platform that provides transactional email, campaign email, and SMTP relay through a REST API. It handles domain authentication (DKIM, SPF), bounce processing, and real-time delivery tracking so your team can focus on product instead of mail infrastructure.
RelayPost handles both transactional emails (password resets, receipts, alerts) and marketing campaigns (newsletters, broadcasts) through a single API.
What you get
Section titled “What you get”- 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
How it works
Section titled “How it works”Your App → RelayPost API (or SMTP) → Email Queue → Delivery Engine → Recipient Inbox ↓ Webhook Events → Your App- You send an email via the API or SMTP
- RelayPost validates, queues, and delivers it
- Delivery events (delivered, bounced, opened) are sent to your webhook URL in real time
Authentication
Section titled “Authentication”RelayPost uses two authentication methods:
| Method | Use case |
|---|---|
| API Key | Programmatic access via the REST API |
| SMTP Credentials | Username/password for SMTP relay connections |
Both are scoped to your organization and managed from the dashboard.
Next steps
Section titled “Next steps”→ Quickstart — send your first email in 5 minutes
Frequently Asked Questions
Section titled “Frequently Asked Questions”What is RelayPost?
Section titled “What is RelayPost?”RelayPost is a developer-first email delivery platform that provides transactional email, campaign email, and SMTP relay through a REST API. It handles domain authentication (DKIM, SPF), bounce processing, and real-time delivery tracking.
How is RelayPost different from SendGrid?
Section titled “How is RelayPost different from SendGrid?”RelayPost is built for developers who want a clean API without marketing-tool complexity. It offers both REST API and SMTP relay, automatic DKIM signing, real-time webhooks, and transparent pricing with a free tier of 100 emails per month.
Is RelayPost free?
Section titled “Is RelayPost free?”RelayPost has a free tier that includes 100 emails per month with full API access, SMTP relay, domain authentication, and webhook tracking. Paid plans start at $5/month for 10,000 emails.
Does RelayPost support SMTP?
Section titled “Does RelayPost support SMTP?”Yes. RelayPost provides an SMTP relay on port 587 (STARTTLS) and 465 (TLS). You can use it as a drop-in replacement for any application that sends email via SMTP — just update your SMTP settings.