Papercut - Papercut Simple Desktop SMTP Server

•    Javascript

Ever need to test emails from an application or web site but don't want them accidently being sent or having to deal with the hassle of setting up a test email server? Papercut is a quick email viewer with a built-in SMTP server designed to only receive messages. It doesn't enforce any restrictions how you send your email. It allows you to view the whole email-chilada: body, html, headers, attachment down to the naughty raw bits. It can be set to run on startup and sits quietly minimized in the tray giving you a balloon popup when a new message arrives.Download Papercut.Setup.exe installer.

DavMail - POP/IMAP/SMTP/Caldav to Exchange

•    Java

DavMail is a POP/IMAP/SMTP/Caldav/Carddav/LDAP exchange gateway allowing users to use any mail/calendar client (e.g. Thunderbird with Lightning or Apple iCal) with an Exchange server, even from the internet or behind a firewall through Outlook Web Access. DavMail now includes an LDAP gateway to Exchange global address book and user personal contacts to allow recipient address completion in mail compose window and full calendar support with attendees free/busy display.

MailDev - :mailbox: SMTP Server + Web Interface for viewing and testing emails during development.

•    Javascript

MailDev is a simple way to test your project's generated emails during development with an easy to use web interface that runs on your machine built on top of Node.js. If you want to use MailDev with Docker, you can use the djfarrelly/maildev image on Docker Hub. For a guide for usage with Docker, checkout the docs.

MailHog - Web and API based SMTP testing

•    Go

MailHog is an email testing tool for developers. Configure your application to use MailHog for SMTP delivery, View messages in the web UI, or retrieve them with the JSON API, Optionally release messages to real SMTP servers for delivery. Inspired by MailCatcher, easier to install.Built with Go - MailHog runs without installation on multiple platforms.

go-guerrilla - Mini SMTP server written in golang

•    Go

Breaking change: The structure of the config has recently changed to accommodate more advanced TLS settings. A lightweight SMTP server written in Go, made for receiving large volumes of mail. To be used as a package in your Go project, or as a stand-alone daemon by running the "guerrillad" binary.

Mail-in-a-Box - One click easy-to-deploy SMTP server

•    Python

Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box. Mail-in-a-Box lets you become your own mail service provider in a few easy steps. It’s sort of like making your own gmail, but one you control from top to bottom. Technically, Mail-in-a-Box turns a fresh cloud computer into a working mail server. But you don’t need to be a technology expert to set it up.

MailCatcher - Catches mail and serves it through a dream

•    Ruby

MailCatcher runs a super simple SMTP server which catches any message sent to it to display in a web interface. Run mailcatcher, set your favourite app to deliver to smtp://127.0.0.1:1025 instead of your default SMTP server, then check out http://127.0.0.1:1080 to see the mail that's arrived so far.

Modoboa - Mail hosting made simple

•    Python

Modoboa is a mail hosting and management platform including a modern and simplified Web User Interface. It provides useful components such as an administration panel or a webmail. Modoboa integrates with well known software such as Postfix or Dovecot. A SQL database (MySQL, PostgreSQL or SQLite) is used as a central point of communication between all components.

Mailin - Artisanal Inbound Emails for Every Web App

•    Python

Mailin is an smtp server that listens for emails, parses them and posts them as json to the url of your choice. It checks the incoming emails dkim, spf, spam score (using spamassassin) and tells you in which language the email is written. Mailin can be used as a standalone application directly from the command line, or embedded inside a node application.

Java Email Server

•    Java

JES is a multi-featured hybrid MTA/MDA server written in the java programming language. It supports TLS, SSL, SMTP authentication, spam control and lot more.

C# Email Server - SMTP and POP3 Email Server in CSharp

•    CSharp

C# Email Server (CES). Implements SMTP and POP3 components that can be used as a standalone server or as components in other applications. It is a port of the Java Email Server (JES). This component allows a program to accept incoming emails and process them using user defined logic.

hMailServer - E-Mail Server for Microsoft Windows.

•    C++

hMailServer is an open source email server for Microsoft Windows. It supports the common e-mail protocols (IMAP, SMTP and POP3) and can easily be integrated with many existing web mail systems. It has flexible score-based spam protection and can attach to your virus scanner to scan all incoming and outgoing email.

smart messaging connector

Sending fax from a PrintDocument or a file. Sending broadcast fax. Managing (Pause/Resume/Restart) current fax job. Managing configuration of the fax server

Mailias

Mailias makes testing of email enabled applications easier for DEVs and QAs. You no longer need to have multiple "real" email addresses to test and validate registration and notification features. You can alias many email address and have your own Mailias. Written in C# thi...

smtp4dev

Windows 7/Vista/XP/2003/2010 compatible dummy SMTP server. Sits in the system tray and does not deliver the received messages. The received messages can be quickly viewed, saved and the source/structure inspected. Useful for testing/debugging software that generates email.

Webadmin - SophiMail Webadmin and Dashboard

•    PHP

SophiMail Webadmin and Dashboard is a universal interface for managing mail-servers built on a Postfix/Dovecot/MySQL back-end. It is like PostfixAdmin, but it also enables the control of multiple mail-servers via 1 single screen.

CRSMail - JAVA based E-Mail server

•    Java

CRSMail a 100% JAVA based E-Mail server. It supports SMTP, POP3, Plugins, Can listen on multiple ports, Log's everything to a log file etc.

magento2-gmail-smtp-app - Configure Magento 2 to send email using Google App, Gmail, Amazon Simple Email Service (SES), Microsoft Office365 and many other SMTP (Simple Mail Transfer Protocol) servers

•    PHP

Configure Magento 2 to send all transactional email using Google App, Gmail, Amazon Simple Email Service (SES), Microsoft Office365 or other SMTP server. Sending transactional emails to customers is a vital part of running an e-commerce store. Our free custom Magento extension integrates with all major email service provider and third-party SMTP server to reliably deliver messages in customers' inbox.

docker-smtp - SMTP docker container

•    Shell

This is a SMTP docker container for sending emails. You can also relay emails to gmail and amazon SES.The container accepts RELAY_NETWORKS environment variable which MUST start with : e.g :192.168.0.0/24 or :192.168.0.0/24:10.0.0.0/16.

aiosmtpd - A reimplementation of the Python stdlib smtpd.py based on asyncio.

•    Python

The Python standard library includes a basic SMTP server in the smtpd module, based on the old asynchronous libraries asyncore and asynchat. These modules are quite old and are definitely showing their age. asyncore and asynchat are difficult APIs to work with, understand, extend, and fix.With the introduction of the asyncio module in Python 3.4, a much better way of doing asynchronous I/O is now available. It seems obvious that an asyncio-based version of the SMTP and related protocols are needed for Python 3. This project brings together several highly experienced Python developers collaborating on this reimplementation.