Open-source alternatives to Sendgrid Go

A simple CSS parser and inliner in Go

MailHog SMTP Protocol

Lightweight SMTP client written in Go

Robust and flexible email library for Go

Golang package for send email. Support keep alive connection, TLS and SSL. Easy for bulk SMTP.

Go library for the Mailgun API.

Using Mailchain, blockchain users can now send and receive rich-media HTML messages with attachments via a blockchain address.

Roundcube is an open-source, self-hosted webmail client designed for reading, composing, and organizing emails stored on remote servers using IMAP and SMTP protocols. It provides a browser-based interface that allows users to manage their mailboxes and sender identities through a secure communication platform. The platform is distinguished by its modular architecture, featuring a plugin-based extension system for adding new functional modules and a skin-based theme layer for customizing the visual appearance and responsive layouts. It further supports embedding its interface into external clo

This branch is for use with CakePHP 5.1+. For details see version map.

Super Simple IMAP Client Library for Golang

Postal is an open-source email infrastructure and self-hosted delivery platform. It functions as an SMTP mail server and inbound email gateway, providing the tools necessary to send and receive email through a privately managed infrastructure. The system manages SMTP infrastructure for outgoing message delivery and provides capabilities for custom email receiving. It allows for the routing of incoming external emails to internal applications or websites for automated processing. The platform includes support for multi-tenant domain mapping, event-driven webhook notifications, and plugin-base

Django-Mailgun A Django email backend for use with Mailgun

Djrill: Mandrill Transactional Email for Django

Simple e-mail sending library

Gibbon is an API wrapper for MailChimp's API

gcourier provides a simple and easy-to-use interface for sending emails from Gleam.

CSS styled emails without the hassle.

Incoming! helps you receive email in your Rack apps.

The express way to send mail from Ruby.

Python SMTP Server for Humans

Django-Db-Mailer

A wrapper for ZeptoMail's transactional email API.

Email library for Crystal. Testable, adapter-based, and catches bugs for you. Comes with an adapter for SendGrid.

Maddy is a modular mail server that assembles a complete email system by connecting small, single-purpose modules through a declarative configuration file. Rather than a monolithic stack, it lets operators compose message processing, storage, authentication, and security enforcement from interchangeable building blocks, with each module handling a specific function like receiving SMTP connections, verifying credentials, or applying policy checks. The server distinguishes itself through its flexible authentication and security architecture. It delegates user verification to external systems in