Postal
Open source mail delivery platform for inbound and outbound email
16.7k stars 1.3k forks last commit first released MIT
Actively maintained
Last commit 3 Jun 2026.
Postal is a fully featured email delivery platform for running your own inbound and outbound mail service. It provides the core components needed to accept, route, and deliver email for applications and domains, similar in scope to hosted transactional email providers.
Key Features
- SMTP service for sending email from applications and services
- Incoming email handling for receiving and processing messages
- Web-based interface for managing organizations, servers, and domains
- Message tracking and log-style visibility into mail delivery
- Designed to operate as a multi-tenant mail platform
- Installation tooling and scripts available to help bootstrap prerequisites
Use Cases
- Self-hosted transactional email platform for web apps and SaaS products
- Centralized mail infrastructure for multiple domains and teams
- Inbound email processing pipelines (for example, support or app workflows)
Limitations and Considerations
- Requires careful DNS and deliverability setup (SPF/DKIM/DMARC) to achieve reliable inbox placement
- Running production email infrastructure typically requires IP reputation management and ongoing monitoring
Postal is well-suited for teams that need control over email sending and receiving infrastructure while retaining a modern management interface. It offers a practical foundation for operating a SendGrid-like mail service on your own servers.
Categories:
Tags:
Tech Stack:
Similar to Postal
Hyvor Relay
Open-source, self-hosted Email API for developers
AGPL-3.0 open-source email API for developers that can be self-hosted; supports SMTP sending, webhooks, DNS automation, observability, multi-tenancy, and project isolation.
OpenTrashmail
Self-hosted disposable email inbox with web UI, API, RSS, webhooks
OpenTrashmail is a standalone disposable email (“trashmail”) service with its own SMTP server, offering a web UI plus JSON API, RSS feeds, and webhooks for received mail.
Exim
Configurable SMTP message transfer agent for Unix-like systems
Exim is an open source SMTP message transfer agent (MTA) for Unix-like systems, offering flexible mail routing and extensive controls for handling inbound email.
Dovel
Simple Go-based SMTP server for receiving and sending mail
Lightweight SMTP server written in Go that receives and sends email via a single JSON config and executable hooks; supports per-user DKIM and TLS.
DocuSeal
Open-source platform for filling and signing documents online
Self-hostable DocuSign alternative to create fillable forms and collect legally binding eSignatures with API and webhooks.
Maddy Mail Server
Composable all-in-one SMTP/IMAP mail server with security features
Go-based, modular mail server implementing SMTP/LMTP/IMAP with built-in DKIM/SPF/DMARC, storage backends (SQLite/Postgres/S3), Prometheus metrics and Docker support.
