Open Source Windows Email Clients
Sort By:
Email Clients for Windows
View 43 business solutionsBrowse free open source Email Clients and projects for Windows below. Use the toggles on the left to filter open source Email Clients by OS, license, language, programming language, and project status.
-
MongoDB Atlas runs apps anywhereMongoDB Atlas gives you the freedom to build and run modern applications anywhere—across AWS, Azure, and Google Cloud. With global availability in over 115 regions, Atlas lets you deploy close to your users, meet compliance needs, and scale with confidence across any geography.
-
Go from Code to Production URL in SecondsSkip the Kubernetes configs. Cloud Run handles HTTPS, scaling, and infrastructure automatically. Two million requests free per month.
-
1
Windows MBox Viewer
Windows eml and mbox viewer.
Free Windows Mbox Viewer. Gain access to mbox archives, single eml or single Outlook messages. View attachments and export single mails in eml format. Access large mbox files such as Google Takeout or Mozilla Thunderbird Archives. Development of mbox viewer continues now at github: https://github.com/eneam/mboxviewer **NOTE**: Windows Defender may sometimes report incorrectly that mbox-viewer contains malware. Please report the case to the development. Development will ask Windows Security to update Windows Defender rules to resolve the issue. Last time the incorrect detection was corrected by Microsoft Security within few hours. User will need to run Windows Update to install the latest updated detection rules. -
2
SquirrelMail is a PHP-based Web email client. It includes built-in pure PHP support for IMAP and SMTP, and renders all pages in pure HTML 4.0 for maximum compatibility across browsers. It has strong MIME support and a flexible plugin system.
-
3
Mailspring
A faster, leaner email client and fork of Nylas Mail
Mailspring is a fast and lean mail client that’s a new version of Nylas Mail. It’s maintained by one of Nylas Mail’s original authors, with plenty of great features and enhancements such as a new C++ sync engine that allows it to use 50% less RAM. Heavy dependencies have also been removed and the package manager rewritten for even greater speed. Written in TypeScript with Electron and React, it is cross-platform (macOS, Windows and Linux) and designed to be easy to extend. -
4
PHPMailer
A full-featured email creation and transfer class for PHP
A PHP email creation and transport class featuring file attachments, SMTP servers, CCs, BCCs, HTML messages, word wrap, and more. Sends email via sendmail, PHP mail(), QMail, or with SMTP. PHPMailer is used by many popular PHP development frameworks and is one of the most popular email-generating and sending libraries in the world. This project is defunct here on sourceforge – it's now maintained on Github at https://github.com/PHPMailer/PHPMailer. Documentation is available at https://github.com/PHPMailer/PHPMailer/wiki -
$300 Free Credits to Build on Google CloudPut your $300 in credit toward real workloads, then keep building with free monthly usage for 20+ products. No commitment and no charge until you upgrade.
-
5
Tutanota
Open source email service with a strong focus on security and privacy
Tutanota is an open source email client focused on security and privacy. It is built with end-to-end encryption and 2FA, so you can be assured of utmost email security. Tutanota is always encrypted, so whether you’re using their secure webmail client, mobile apps or desktop clients, you can be sure to communicate securely. -
6
Outlook Mail Merge Attachment is a script which can be used to add an attachment to an mail merge in Microsoft Outlook.
-
7
PoptrayU
Email Notifier For Windows
This email notifier sits in your system tray and pops up a notification when new messages arrive. Preview your email before downloading it to your mail client or launching webmail applications. Create rules to delete or change the priority of messages. This program builds upon the open source PopTray mail notifier adding many new features including Windows Vista/7/8/10 support, UTF-8 and unicode support, HTML Preview, IMAP support, TLS & SASL support, etc. -
8
RainLoop Webmail
Simple, modern & fast web-based email client
RainLoop Webmail is a modern, fast, and lightweight web-based email client. It supports IMAP and SMTP protocols, allowing users to access and manage their email accounts through a web interface. RainLoop offers features like multi-account support, a responsive UI, and integration with popular email providers. It is self-hosted, giving users control over their email data. -
9
Proton Mail Bridge
Proton Mail Bridge application
Proton Mail Bridge is a desktop application that runs in the background on Windows, macOS, and Linux to enable users to access their Proton Mail encrypted email accounts with traditional email clients like Outlook, Thunderbird, Apple Mail, and others via local IMAP/SMTP servers. Because standard IMAP cannot natively decrypt end-to-end encrypted messages, Bridge acts as a translator that downloads encrypted mail, decrypts it locally, and serves it to your preferred mail client over a local server, while encrypting outgoing messages before they’re sent to Proton’s servers. It provides a seamless integration layer for users who need offline support, familiar local client workflows, or tighter integration with desktop tools while preserving Proton’s zero-access encryption model. The Bridge app continues running even when its GUI is closed so that mail clients can remain connected and synchronized, and it supports automatic startup and robust credential handling via secure storage. -
Build Agents and Models on One PlatformGemini Enterprise Agent Platform is Google Cloud's comprehensive platform for developers to build, scale, govern, and optimize agents and models. Choose from Google's most advanced models and third-party models like Anthropic's Claude Model Family.
-
10
-
11
PopTray is a mail notifier written in Delphi for the Windows platform. It sits in your tray notification area and check mail from multiple accounts on a timer interval. Preview, Delete, Rules, Plug-ins and translated into more than 30 languages.
-
12
Magic Mail Monitor3 - Windows mail checker with multiple mailboxes support, ability to preview and delete messages. Based on original code of Magic Mail Monitor from Valeriy Ovechkin.
-
13
HERMES Mail
The cult-favourite eMail client formerly known as Qualcomm Eudora
eMail traffic is on the rise. With over 100 man-years of development time behind it and a clean, intuitive interface that makes handling messages a breeze, Hermes Messenger (formerly known as QUALCOMM Eudora) is more than a way to send and receive mail: it's a powerful management tool with features to increase your productivity and enhance your communications. It is the best eMail program for people who get lots of it. If you're not yet one of them, you soon will be. Take control of your eMail before it takes control of you! Hermes provides industrial-strength communication, free of ads and free of cost. -
14
Cypht
Lightweight Open Source webmail written in PHP and JavaScript
All your E-mail, from all your accounts, in one place. Cypht is not your father's webmail. Unless you are one of my daughters, in which case it is your father's webmail. Cypht is like a news reader, but for E-mail. Cypht does not replace your existing accounts - it combines them into one. And it's also a news reader. The driving force behind Cypht development is to provide combined views for multiple accounts, but it's also a standard E-mail client that lets you browse and manage IMAP folders and send outbound messages with SMTP. Cypht is an application built entirely of plugins, or as we call them, module sets (which is obviously way cooler sounding than plugins), that are executed by the framework. Modules provide a flexible way to add new features or customize the program without hacking the code. Cypht is Open Source (LGPL V2), and written in PHP and JavaScript. -
15
Columba is an email client written in Java, featuring a user-friendly graphical interface with wizards and internalionalization support. Its a powerful mail management tool with features to enhance your productivity and communication.
-
16
Hastymail is a fast, secure, rfc-compliant, cross-platform IMAP/SMTP client application written in PHP providing a clean web interface for sending and reading E-mail. This version of Hastymail is no longer being developed. We are now working on a new version, Hastymail 3, AKA, "Cypht". http://cypht.org
-
17
Mail Notifier
Mail Notifer for Windows
Mail Notifier is free, modern email notifier with the latest user interface trends for Windows 10/11. It supports multiple accounts and IMAP/POP3 protocols. Enjoy customizable notifications, message previews, and more, all in 34 languages! For more details, please refer to the readme.txt file (Files tab, description below). Note: Gmail support is currently unavailable due to verification requirements by Google. Note: Outlook.com support is currently unavailable due to moving to OAuth2 authentication from login/password at Outlook servers. -
18
-
19
G4J is a set of API that communicate to GMail. Use this API to login, retrive/search/browse message, download attachment and do others action on GMail account! An email application (Gmailer for java) is included to demonstrate the usage of the API.
-
20
MultiMail is an offline mail packet reader for Unix and other systems. It currently supports the Blue Wave, QWK, OMEN, OPX and SOUP formats. It has a full screen, color user interface, built with the curses library.
-
21
MorphyMail Free Email Marketer
Create, send and track Unlimited bulk emails for Free
Desktop software for windows to create, send and track unlimited bulk emails for lifetime for free. Includes 500 email templates , automated bounce and subscription processing, spam checker, WYSIWYG HTML editor, google analytics and social media integration, automated delivery tracking to track opens , clicks and geolocation of recipients, multithreaded engine for fast delivery of emails, website forms integration, scheduled mailing and much more features. It is a 100% free software to send unlimited bulk emails for lifetime. -
22
-
23
It is an email sender. This software can send your mass marketing bulk email to unlimited mailing list. The program can send via SMTP server, MAPI, or delivers e-mail directly without ISP's mail system. Also includes flexible address filters and rules.
-
24
Aegis Implicit Mail (AIM)
Send Mime and Smime Emails to Any Type of Mail Server
Aegis Implicit Mail is a free and open source library which is designed to provide fast and developer friendly API to send emails using SMTP ports. Binaries are available in the form of NuGet package: https://www.nuget.org/packages/AIM Please check http://pki.tools/aim.html as well AIM Supports : * None Ssl Mails * Implicit Ssl Mails * Explicit Ssl Mails * Smtp Connection test * Detect Ssl type of mail server * Attachments for MIME and S/MIME message. * In-line attachment and separate file attachment * All content types and mimes * SMIME , Signed and Encrypted mails In an integrated way Sadly, Microsoft.Net.Mail Ssl Mails does not support Implicit Ssl Mail and it is still used by many servers, including port 465 of Gmail here AIM comes to make a readable and fast alternative to send your smtp mails. For unicode issues please refer to https://sourceforge.net/p/netimplicitssl/tickets/4/ . We really appriciate any help in testing of different encodings -
25
NOCC is a simple and fast Webmail client which can handle POP3 and IMAP mailboxes and sends email via SMTP. It is written with PHP, has low requirements (no database, frames). Features multi-language support, MIME attachments, displays HTML messages. The installation guide comes with the source code: https://sourceforge.net/p/nocc/code/HEAD/tree/trunk/webmail/docs/INSTALL If you encounter problems or bugs you can always try the current HEAD version: https://sourceforge.net/p/nocc/code/HEAD/tarball?path= Questions, bug reports or support requests are very welcome: https://sourceforge.net/p/nocc/_list/tickets Alternative source code repository: https://github.com/oheil/NOCC
