Introduction

Posta is a self-hosted, open-source email delivery platform that gives developers full control over their email infrastructure. It provides a developer-friendly REST API for sending emails, managing templates, tracking delivery, and monitoring analytics — all without relying on third-party services like SendGrid or Mailgun.

Why Posta?

• Self-hosted — Your data stays on your servers. No vendor lock-in.
• Developer-first — Clean REST API with official SDKs for Go, PHP, and Java.
• Full-featured — Templates with versioning and localization, SMTP management, domain verification, webhooks, analytics, and more.
• Open source — Licensed under Apache 2.0. Contribute, fork, or customize as needed.

Key Features

Feature	Description
Email Delivery	Send single, template, and batch emails via REST API with scheduled sending and automatic retries
Templates	Version-controlled templates with multi-language support, variable substitution, and stylesheet inlining
SMTP Management	Configure multiple SMTP servers with TLS support and shared pools
Domain Verification	SPF, DKIM, and DMARC record verification with verified sender enforcement
Contacts & Suppression	Contact tracking, segmentation, bounce handling, and automatic suppression lists
Subscribers & Lists	Subscriber management with static and dynamic lists, bulk import, and custom fields
Campaigns	Template-based bulk sending with scheduling, A/B testing, throttling, and analytics
Webhooks & Events	Real-time HTTP notifications with retry strategies and delivery tracking
Analytics	Email delivery metrics, trends, bounce rates, and daily reports
Security	API keys, JWT auth, 2FA (TOTP), OAuth / SSO, rate limiting, IP allowlists
Workspaces	Multi-tenant architecture with role-based access and scoped API keys
Admin Panel	User management, platform metrics, shared SMTP pool, OAuth providers, and platform settings
Dashboard	Vue-based web UI for managing all resources with dark/light mode
GDPR Compliance	Data export, import, and deletion
Prometheus Metrics	Built-in observability for production monitoring

API Reference

Posta provides interactive API documentation:

• Swagger UI — https://app.goposta.dev/docs
• OpenAPI spec — https://app.goposta.dev/openapi.json

When running locally, the docs are available at /docs on your Posta instance.

Architecture

Posta is built with:

• Go backend using the Okapi web framework
• PostgreSQL for persistent storage
• Redis for job queues (via Asynq) and caching
• Vue 3 dashboard (embedded or standalone)

┌─────────────┐     ┌─────────────┐     ┌──────────────┐
│  Your App   │────▶│  Posta API  │────▶│  PostgreSQL  │
│  (SDK/HTTP) │     │  (Go)       │     └──────────────┘
└─────────────┘     │             │     ┌──────────────┐
                    │             │────▶│  Redis       │
                    └──────┬──────┘     └──────────────┘
                           │
                    ┌──────▼──────┐     ┌──────────────┐
                    │   Worker    │────▶│  SMTP Server │
                    │  (Asynq)   │     └──────────────┘
                    └─────────────┘

Next Steps

• Installation — Deploy Posta with Docker or from source
• Configuration — Configure environment variables
• Quick Start — Send your first email in minutes