Email Clients for Linux

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Browse 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.

  • Iris Powered By Generali - Iris puts your customer in control of their identity. Icon
    Iris Powered By Generali - Iris puts your customer in control of their identity.

    Increase customer and employee retention by offering Onwatch identity protection today.

    Iris Identity Protection API sends identity monitoring and alerts data into your existing digital environment – an ideal solution for businesses that are looking to offer their customers identity protection services without having to build a new product or app from scratch.
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  • Rezku Point of Sale Icon
    Rezku Point of Sale

    Designed for Real-World Restaurant Operations

    Rezku is an all-inclusive ordering platform and management solution for all types of restaurant and bar concepts. You can now get a fully custom branded downloadable smartphone ordering app for your restaurant exclusively from Rezku.
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  • 1
    Windows MBox Viewer

    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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    Downloads: 1,488 This Week
    Last Update:
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  • 2
    SquirrelMail
    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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    Downloads: 410 This Week
    Last Update:
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  • 3
    Mailspring

    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.
    Downloads: 62 This Week
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  • 4
    PHPMailer

    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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    Downloads: 106 This Week
    Last Update:
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  • Collect! is a highly configurable debt collection software Icon
    Collect! is a highly configurable debt collection software

    Everything that matters to debt collection, all in one solution.

    The flexible & scalable debt collection software built to automate your workflow. From startup to enterprise, we have the solution for you.
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  • 5
    Tutanota

    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.
    Downloads: 10 This Week
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  • 6
    Trojitá, a Qt IMAP e-mail client
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    Downloads: 87 This Week
    Last Update:
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  • 7
    threadkey

    threadkey

    Add keyboard shortcuts to switch between different thread views

    Strike the 'T' key to sort messages by thread, strike the 'U' key to sort unthreaded again, just like the 'G' key switches to Grouped By Sort view.
    Downloads: 151 This Week
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  • 8
    Proton Mail Bridge

    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.
    Downloads: 4 This Week
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  • 9
    RainLoop Webmail

    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.
    Downloads: 3 This Week
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  • Failed Payment Recovery for Subscription Businesses Icon
    Failed Payment Recovery for Subscription Businesses

    For subscription companies searching for a failed payment recovery solution to grow revenue, and retain customers.

    FlexPay’s innovative platform uses multiple technologies to achieve the highest number of retained customers, resulting in reduced involuntary churn, longer life span after recovery, and higher revenue. Leading brands like LegalZoom, Hooked on Phonics, and ClinicSense trust FlexPay to recover failed payments, reduce churn, and increase customer lifetime value.
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  • 10
    Proton Web Clients

    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.
    Downloads: 2 This Week
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  • 11
    PHP app to access Gmail/Googlemail/Gmail-for-Your-Domain accounts on wireless devices. Convenient alternative access method to your email account on the move, gmail-mobile incorporates as many Gmail features as possible within limits of a mobile device.
    Downloads: 6 This Week
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  • 12
    Cypht

    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.
    Downloads: 1 This Week
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  • 13
    Claws Mail
    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.
    Downloads: 25 This Week
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  • 14
    Hastymail
    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
    Downloads: 7 This Week
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  • 15
    Outlook Open Converter

    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!
    Downloads: 8 This Week
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  • 16
    Add support for making Gmail the default mail application for the GNOME desktop. "Gmail" will be a choice for Mail Reader in the Preferred Applications dialog. "Mailto" links, "Send Link", etc., will be handled by Gmail.
    Downloads: 3 This Week
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  • 17
    NOCC
    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
    Downloads: 3 This Week
    Last Update:
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  • 18
    Columba
    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.
    Downloads: 4 This Week
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  • 19
    AlphaMail is an accelerated web mail interface with a C++ middleware layer that is more effective than an IMAP proxy which is a highly scalable (10k+ users). The interface includes modern features, Section 508 compliance, and universal browser support.
    Downloads: 10 This Week
    Last Update:
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  • 20
    GoldBug - Encrypted Communications

    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
    Downloads: 9 This Week
    Last Update:
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  • 21
    MultiMail Offline Reader
    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.
    Downloads: 5 This Week
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  • 22
    OpenChange Project

    OpenChange Project

    Microsoft Exchange compatible server and client libraries

    OpenChange is a portable Open Source implementation of Microsoft Exchange server and Exchange protocols. It provides a complete solution to interoperate with Microsoft Outlook clients or Microsoft Exchange servers. OpenChange client-side library is used in existing messaging clients and is the solution in new projects to communicate natively with Microsoft Exchange and Exchange-compatible servers. OpenChange server is a transparent Microsoft Exchange server replacement using native Exchange protocols and does not require any plugin installation in Outlook.
    Downloads: 3 This Week
    Last Update:
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  • 23
    Heirloom mailx (formerly known as "nail") is intended provide the functionality of the POSIX mailx command with additional support for MIME messages, IMAP (including caching), POP3, SMTP, S/MIME, message threading/sorting, scoring, and filtering.
    Downloads: 4 This Week
    Last Update:
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  • 24
    IGSuite - Integrated Groupware Suite

    IGSuite - Integrated Groupware Suite

    IGSuite is a web-ajax-based Integrated Groupware Suite

    IGSuite is a web-based Integrated Groupware Suite oriented to be a CRM solution. In the Suite you can find: IGWebMail, IGCalendar, IGContacts, IGArchive, IGWiki, IGTodo, IGChat, Projects, IGFax an HylaFax client, IGFileManager, IGMsg and many other.
    Downloads: 2 This Week
    Last Update:
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  • 25
    EGroupware Enterprise Collaboration
    EGroupware has moved to Github, please find all our downloads there: https://github.com/EGroupware/egroupware/releases EGroupware is a multi-user, web-based groupware suite. Currently available modules include: email, addressbook, calendar, infolog (notes, to-do's, phone calls), content management, wiki, project management, tracker, timesheet, knowledge base, CalDAV/CardDAV
    Downloads: 1 This Week
    Last Update:
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