Open Source Linux Email Clients
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Email Clients for Linux
View 25 business solutionsBrowse free open source Email Clients and projects for Linux below. Use the toggles on the left to filter open source Email Clients by OS, license, language, programming language, and project status.
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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. -
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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.
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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. -
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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. -
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Meru
Gmail desktop app for macOS, Windows & Linux (formerly Gmail Desktop)
Meru, formerly Gmail Desktop, is an open-source desktop email application designed to provide a dedicated Gmail experience outside the web browser. It allows users to access their Gmail inboxes through an independent application for Windows, macOS, and Linux. The software supports multiple Gmail accounts and provides native desktop notifications for incoming messages. It includes advertisement and tracker blocking to reduce distractions while managing email. Security features include confirmation prompts for unfamiliar links to help prevent accidental visits to suspicious websites. Meru also supports customizable Gmail styles and conversation display options. Built with Electron, the application processes email interactions locally while keeping messages within Google's infrastructure. -
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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. -
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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 -
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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. -
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Proton Web Clients
Monorepo hosting the proton web clients
Proton Web Clients is a monorepo hosting the web applications for Proton’s suite of privacy-focused services, including the core Proton Mail webmail interface and related web apps like Proton Calendar, Proton Drive, Proton Account, Proton VPN, Proton Pass, and other connected tools. It consolidates all web client code, shared modules, dependencies, and development tooling into a single repository, enabling unified maintenance, consistency of design patterns, and efficient evolution of Proton’s online interfaces. These web clients run entirely in the browser, letting users securely interact with their email, calendars, files, and other services without needing native software installed, and benefiting from end-to-end encryption where applicable. The monorepo includes application logic, UI components, build scripts, and testing infrastructure for reliable deployments and streamlined continuous integration. -
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Meron
Fast, secure email client with chat and kanban views
Meron is a free, open-source email client designed to combine traditional email management with chat-style conversations and Kanban organization. It provides a unified inbox for managing multiple email accounts through IMAP and SMTP. Users can switch between conventional email, threaded chat, and Kanban board views. The software includes customizable tags, automated filtering rules, and rich-text message composition. It also supports RSS and Atom feeds for following online publications. Security features include encrypted local storage and credentials protected by the operating system's keyring. Optional Model Context Protocol integration allows AI clients to access permitted email functions. Available for Windows, macOS, Linux, Android, and iOS, Meron provides a flexible communication workspace. -
11
mail
Built from the ground up for speed
Flectar Mail is an open-source email, calendar, and contact management application built with Rust for native performance and low memory consumption. It supports Windows, macOS, Linux, Android, and iOS, with mobile installation availability varying by platform. Users can connect Gmail, Outlook, Microsoft 365, and standards-based email services through IMAP, POP3, SMTP, and JMAP. Its interface organizes messages into conversation threads, tabs, and color-coded account profiles. CalDAV and CardDAV integration provides synchronized calendars and contacts. Offline storage keeps previously synchronized messages and information accessible without an internet connection. Security features include remote image blocking and native HTML rendering without executing email scripts. Additional capabilities include attachment searches, OpenPGP encryption, customizable themes, and local backups. -
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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. -
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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
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unimail-client
This is the first executable client program of Unimail
Unimail Client is a free, open-source command-line application for sending emails through the Unimail service. Built with Go, it uses the Unimail Go SDK to handle email delivery requests. Users can send plain-text messages or formatted HTML emails directly from a terminal. The application supports multiple recipients, carbon copies, blind carbon copies, and file attachments. API authentication can be configured through an environment variable or supplied with a command-line option. Routing parameters provide additional control over how messages are submitted. Built-in commands display version information, usage instructions, and available updates. Unimail Client can be integrated into scripts and automated workflows, with installation options for Windows and Linux. -
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Claws Mail is a GTK+ based, lightweight, and fast e-mail client and newsreader. Supports POP3, APOP, IMAP, SMTP, SMTP AUTH, NNTP, LDAP, multiple accounts, spell-checking, addressbook, SSL, GPG, filtering, i18n, & more. It is further extended by plugins.
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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
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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.
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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.
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exmh is a user interface to the MH (a.k.a. nmh) email system. It is extensible and its users have exploited this to integrate PGP, Glimpse, ispell, faces/picons, MIME, and much more.
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jwSMTP, Send email programmatically (C++ code/lib). Linux, BSD, Windows etc. Attachments, Multiple recipients, Cc/Bcc recipients supported. MX lookup or send to an SMTP server direct. LOGIN and PLAIN authentication now supported. Html or plain text forma
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Outlook Open Converter
Convert Outlook and Outlook Express files to open formats
Tiny application based on readpst and dbxconv that provides a convenient GUI to convert Outlook and Outlook Express files into open standards. The program converts Outlook Express 5/6 .DBX to .EML and Outlook 2003/2007/2010 .PST to MBOX. The program runs only on Linux machines and doesn't need any Microsoft software! -
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GoldBug - Encrypted Communications
Chat Messenger. E-Mail-Client. Websearch. Filetransfer.
GoldBug is a decentralized & secure communication suite that offers an integrated e-mail client, an instant messenger & a file transfer. Also included is an URL-RSS-DB & a p2p web search. Current vers. w/ McEliece Algorithm. GoldBug has been 2013 - 2023 ten years just another Graphical User Interface of the Spot-On Encryption Suite. Main GUI features: Minimal & colorful Interface with Tabs in the East. Microsoft & Qt MinGW deprecated Win32 & for Compiling: ● https://sourceforge.net/p/goldbug/wiki/compiling As Spot-On implemented the minimal GB-concept & Nuvola Icons, GoldBug has now been fully integrated into Spot-On Win64: Just choose Tabs at East & Mini-View in Options - w/ Nuvola Icons of course! Voilá! & Many Thanks, Pro-Files can be found archived at ● current source: https://github.com/textbrowser/spot-on ● EN Manual: https://www.amazon.com/dp/3749435065 ● DE: https://compendio.github.io/goldbug-manual-de/ ● Study: https://www.amazon.com/asin/dp/3750408971 -
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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.
