Email is still one of the most important ways we communicate, whether for work, staying in touch with friends, or managing daily tasks. The right email client can greatly affect how efficiently you stay organized and productive. While there are numerous expensive, proprietary email programs, open-source alternatives provide a welcome balance of freedom, customization, and openness. For Windows users, these open-source email apps offer crucial functionality and give you more control over your experience. In this post, we’ll look at some of the best open-source email clients for Windows and what sets them apart.
The Advantages of Open-Source Email Clients:
There are numerous significant benefits to using an open-source email client, including:
a). Transparency and Security:
Since the source code can be examined, you can be confident there are no vulnerabilities or hidden trackers, making it an excellent choice for anyone worried about security.
b). Customization:
You can usually alter the functionality and interface of open-source email clients to your own preferences thanks to their high degree of customization.
c). Support from the Community:
Open-source projects usually have vibrant communities that provide ongoing support, bug fixes, and feature upgrades.
d). Flexibility:
A large range of email protocols, such as IMAP, POP3, and SMTP, are supported by numerous open-source email clients.
Choosing an email client that aligns with your needs is essential, and open-source software provides a great solution for those who prioritize flexibility, security, and community-driven development. Below are some of the best open-source email clients available for Windows users.
1. Overview of Mozilla Thunderbird:
With a great degree of flexibility and a large feature set, Mozilla Thunderbird is one of the most popular open-source email clients. Created by the Mozilla Foundation, Thunderbird is updated frequently to be up to speed with contemporary email standards. There is something for everyone in Thunderbird, regardless of user skill level.
Key Features:
✔Multi-account Support:
Thunderbird allows you to manage multiple email accounts (IMAP, POP3, and SMTP) within a single interface.
✔Tabbed Email Interface:
Thunderbird facilitates tabbed email navigation, which makes multitasking easier, much like a web browser.
✔Add-ons & Customization:
Thunderbird’s functionality may be improved with a vast library of add-ons, which includes sophisticated spam filters, calendar integration, and even unique themes.
✔Security Features:
To ensure secure communication with others, Thunderbird comes with built-in support for encryption standards like S/MIME and OpenPGP.
✔Smart Folders:
Thunderbird’s intelligent folders allow for automatic email classification, assisting you in grouping emails according to specific parameters such as sender, date, or subject.
What makes Thunderbird the best option? Thunderbird is an excellent choice for both personal and business use due to its design, security features, and many customization choices. Mozilla’s continuous updates enable it to stay up with rapidly evolving email technologies.
2. eM Client:
While not entirely open-source, eM Client offers a feature-rich free version that connects to well-known services like Microsoft Exchange, iCloud, and Gmail. Due to its stylish, modern design and easy setup, eM Client is a compelling alternative for anyone searching for a productive, all-in-one email solution.
Key Features:
✔Unified Inbox:
eM Client allows you to integrate several email accounts into a single, manageable inbox.
✔Calendar and Contacts:
It has a built-in calendar and contact manager to help you manage your communication and scheduling.
✔Chat Integration:
eM Client supports numerous messaging protocols, including Google Hangouts, Jabber, and others, allowing you to communicate directly with the client.
✔Encryption:
Full support for email encryption (PGP and S/MIME) ensures that your communications remain private.
✔Cloud Services Support:
You can simply sync your emails, contacts, and calendars using a smooth connection to Google, iCloud, and other cloud-based services.
Why Choose eM Client? eM Client finds a mix of user-friendliness and powerful capabilities, making it suitable for both personal and professional use. Its slick design and multi-account support make email management a snap.
3. Overview of Claws Mail:
Claws Mail is a quick and simple email client. Targeting experienced users, it handles emails in a simple way while offering an extensive list of features for those that require them.
Key features:
🔸️Advanced Filtering:
Claws Mail supports extensive email filtering, allowing you to easily sort and categorize incoming emails using customizable criteria.
🔸️Multiple Accounts Support:
It supports a variety of email protocols, including POP3 and IMAP, allowing users to manage several accounts simultaneously.
🔸️Plugin Architecture:
Claws Mail’s functionality can be extended with various plugins, such as RSS feed readers or task management tools.
🔸️Customizable Interface:
The minimalist design allows for extensive customization with various themes and settings to fit individual preferences.
🔸️Security:
The built-in support for encryption technologies such as PGP and S/MIME ensures that your communications are safe.
Why Choose Claws Mail? Claws Mail is ideal for people who want a quick, lightweight email client without irrelevant functionality. Its efficiency, combined with significant customization options, makes it a fantastic alternative for expert users seeking complete control over their email experience.
4. Mailpile
Overview: Mailpile is a newer open-source email client that places a strong emphasis on privacy and security. It combines current email functionality with a focus on local storage and end-to-end encryption, making it an attractive option for privacy-conscious users.
Key features:
🔹️Mailpile prioritizes user privacy by enabling end-to-end encryption for safe email communications.
🔹️Emails are easily found and organized because of its robust search engine and smart tagging system.
🔹️The full integration with OpenPGP for email encryption and signatures ensures the security of your communications.
🔹️Mailpile provides complete control over your data by keeping emails locally on your computer, as opposed to several cloud-based email systems.
🔹️Mailpile’s web-based interface allows you to see emails from any local network browser.
Why Mailpile is the Best Choice? Mailpile is the best substitute for anyone worried about the security and privacy of their emails. If you would like to manage your emails in a strong encrypted, locally stored environment, you should utilize Mailpile.
5) Sylpheed
Overview: Sylpheed is a lightweight email client noted for its speed and efficiency. It’s especially well-suited for those searching for a simple, straightforward email management solution, and it shares most of its coding with Claws Mail but has a more minimalist style.
Key Features:
🔸️High Performance:
Sylpheed is speed and performance-tuned, making it an excellent alternative for users with outdated technology or those who appreciate responsiveness.
🔸️Numerous Account Support:
Use IMAP, POP3, and SMTP protocols to manage numerous email accounts.
🔸️PGP Encryption:
Sylpheed offers support for PGP encryption, keeping your communications secure.
🔸️Simple Interface:
Sylpheed’s clean and minimalistic interface can be customized with themes to suit your preferences.
🔸️Filtering and Sorting:
Advanced filtering and sorting options make managing large volumes of email more efficient.
Sylpheed: Why Choose It? For those who require an effective, uncomplicated email client that prioritizes speed and simplicity above unnecessary features, Sylpheed is ideal. It’s perfect for anyone who wants a simple, useful solution for email management.
6. Mailspring
Mailspring is a modern email client with a beautiful look and extensive capabilities. The open-source version is feature-rich, however, several complex functions are reserved for the expensive pro version. It is intended to be fast and user-friendly while also providing several customization choices.
Key Features:
✔Cross-Platform Support:
Mailspring is compatible with several operating systems, including Linux, macOS, and Windows.
✔Unified Inbox:
Email organization is made easier by being able to handle all of your accounts from a single, central interface.
✔Email Snooze & Scheduling:
Mailspring helps you better manage your inbox with tools like email snooze and scheduling.
✔Advanced Search:
Mailspring includes a powerful search feature that makes finding specific emails fast and intuitive.
✔Customization:
With various themes and layout options, Mailspring offers a visually appealing experience that can be made to your preferences.
Why Choose Mailspring? Mailspring is an excellent option for users who appreciate modern features, a clean interface, and powerful search functionality. It’s particularly suited for users who manage multiple email accounts and need a feature-packed, visually appealing client.
Choosing the Right Open-Source Email Client
To manage your emails successfully and efficiently, you must choose the best open-source email client for your requirements. There are several different email clients with different features, performance levels, and customization options. Making the best decision requires considering the following factors:
1️⃣Features:
Think about the fundamental duties you must carry out. For example, do you need email services that link with your calendar, advanced contact management, or task management? Some clients support several email protocols, including IMAP, POP3, SMTP, and even encryption settings. Prioritize features like offline access, productivity tools, and spam filtering that improve your workflow.
2️⃣User Interface:
The design and usability of the email client can significantly impact your experience. Do you prefer a sleek and minimalist interface with only the essentials or a more feature-packed interface with extensive options and tools? Make sure the layout and design match your preferences, as a more intuitive interface can improve your email management and efficiency.
3️⃣Customization:
Open-source email clients often allow a higher degree of customization compared to proprietary ones. Do you need to tweak the client’s appearance, functionality, or integration with third-party tools? Some clients may offer themes, plugins, or code modifications to suit your specific requirements, allowing you to personalize the client’s look and behavior to fit your needs.
4️⃣Community Support:
One significant advantage of open-source software is the vibrant and dynamic community that surrounds it. A strong community can be quite beneficial when it comes to troubleshooting, resolving technical issues, or gathering ideas on how to personalize the client. A client with full documentation, thorough tutorials, and an active forum or user group where you can share information with others is also something you should seek out.
5️⃣Security & Privacy:
Since email communication often contains sensitive information, it’s vital to ensure that the email client supports strong encryption, both for incoming and outgoing messages. Look for features such as end-to-end encryption, secure authentication methods, and data protection protocols to safeguard your privacy.
6️⃣Performance & Compatibility:
The speed and stability of the email client should align with your expectations. Does it run smoothly on your system? Is it compatible with your operating system and the devices you use? Additionally, some clients work better with certain email providers, so make sure that the email client is fully compatible with your existing email service.
Conclusion
The ideal open-source email client for you will be determined by your unique needs. Thunderbird and eM Client are the best options for consumers who require a complete email solution due to their extensive feature sets. Claws Mail and Sylpheed provide lightweight, efficient solutions for individuals that prioritize simplicity and speed. Mailpile is an excellent choice for privacy-conscious individuals because it provides both local storage and encryption. Finally, for customers who value an attractive design and a wide range of capabilities, Mailspring provides a modern, advanced solution with strong features.
By opting for an open-source email client, you gain greater control over your email experience, with the added benefit of supporting the open-source community. Each of these email clients brings something unique to the table, ensuring that there’s a perfect choice for every user.
Reviews, comparison, screenshots and more for the 3 top open-source email clients for Windows.
Written by
Forward Email Team
Time to read
Less than 5 minutes< 5 minutes
Email Client Screenshots
⭐ RecommendedJavaScript & C++
Mozilla Thunderbird
⭐ RecommendedJavaScript & C++
Mozilla Thunderbird is an open-source email client for Windows and is written in the JavaScript & C++ programming language. The official description from its website says, «Access all your messages, calendars, and contacts in one fast app.«
C (GTK)
Claws Mail
C (GTK)
Claws Mail is an open-source email client for Windows and is written in the C (GTK) programming language. The official description from its website says, «Claws Mail is an email client (and news reader), based on GTK+…«
C & GTK+
Sylpheed
C & GTK+
Sylpheed is an open-source email client for Windows and is written in the C & GTK+ programming language. The official description from its website says, «Sylpheed is a simple, lightweight but featureful, and easy-to-use e-mail client.«
Email Client Comparison
(Scroll to the right to see entire table)
P.S. Don’t worry – we’re coming out with our own desktop, mobile, and web apps soon!
Notice of Non-Affiliation and Disclaimer: We are not affiliated, associated, authorized, endorsed by, or in any way officially connected with Mozilla Thunderbird, Claws Mail, and Sylpheed, or any of its subsidiaries or its affiliates. The name Mozilla Thunderbird, Claws Mail, and Sylpheed as well as related names, marks, emblems, and images are registered trademarks of their respective owners.
Email remains an essential communication tool for both personal and professional use.
While many users opt for web-based services, desktop email clients continue to offer advantages in terms of privacy, customization, and offline access.
Open source email clients, in particular, provide transparency, community support, and freedom from vendor lock-in.
These applications are developed by passionate communities committed to privacy, security, and user-centered design.
This guide explores some of the best free open source email clients available today, highlighting their unique features and helping you find the perfect solution for your email management needs.
Let’s dive in.
1. Mozilla Thunderbird
Mozilla Thunderbird stands as one of the most established and comprehensive open source email clients available.
Developed by the same organization behind Firefox, Thunderbird offers a robust feature set that includes support for multiple email accounts, customizable tags and filters, and an integrated calendar.
The client excels at managing high volumes of emails through its advanced search capabilities and quick filtering tools.
Its open source nature has fostered a thriving extension ecosystem, allowing users to enhance functionality with add-ons for encryption, contact management, and productivity tools.
Thunderbird’s cross-platform compatibility (Windows, macOS, and Linux) ensures users can maintain a consistent experience across different operating systems, while its commitment to security includes built-in phishing protection and regular security updates.
The client’s interface, while initially appearing somewhat dated, offers extensive customization options that allow users to create a personalized email environment tailored to their specific workflows.
Also Read: Best Anonymous Email Account Providers
2. BlueMail
BlueMail offers a polished, feature-rich email experience that bridges the gap between open source principles and commercial-grade user experience.
After transitioning to open source in 2019, this cross-platform client has maintained its sophisticated interface while opening its development to community contributions.
BlueMail excels at handling multiple email accounts with intelligent grouping features that automatically categorize messages based on content and sender.
The client’s “People Toggle” view organizes emails by sender rather than chronology, creating a more conversation-centric experience similar to messaging applications.
BlueMail includes advanced scheduling features, allowing users to snooze emails until relevant times or schedule outgoing messages for optimal delivery.
The application’s calendar integration provides seamless coordination between email communications and scheduling, with natural language processing that can automatically detect and suggest adding events mentioned in messages.
BlueMail’s mobile applications offer particular attention to usability with gesture controls and notification customization that make on-the-go email management more efficient.
While maintaining its premium tier for additional features, BlueMail’s core functionality remains free and open source, providing a compelling option for users seeking polished design alongside transparency.
Explore: Best Free Email Account Providers
3. K-9 Mail
K-9 Mail has established itself as the premier open source email client for Android devices, offering a level of control and privacy rarely found in mobile email applications.
This lightweight yet powerful client supports multiple accounts, IMAP push email, and offers extensive customization options for notifications, display settings, and account-specific signatures.
K-9 Mail’s focus on security is evident in its support for OpenPGP encryption through integration with OpenKeychain, allowing users to exchange encrypted messages directly from their mobile devices.
The client’s efficient offline operation enables users to compose, read, and organize emails without an internet connection, with changes synchronizing once connectivity is restored.
While K-9’s interface initially presents a learning curve compared to some mainstream email apps, its logical organization and customization options ultimately create a highly efficient email workflow.
The application’s active development community continually enhances features and addresses security concerns, making it a trustworthy solution for privacy-conscious mobile users.
4. Nylas Mail
Nylas Mail combines sophisticated design with powerful functionality in an open source package that appeals to both casual users and professionals.
Built on modern web technologies, this cross-platform client offers a clean, intuitive interface while supporting advanced features like conversation tracking, send later, and rich contact profiles.
Nylas excels at handling multiple accounts from various providers, presenting them in a unified inbox with customizable views and sorting options.
The client’s plugin architecture encourages community contributions, resulting in extensions for encryption, productivity tools, and service integrations.
Nylas Mail’s search functionality provides contextual results that include both message content and attachment information, making it easy to locate specific items in large email archives.
The application includes robust keyboard shortcuts for efficient navigation and operation, appealing to power users who prefer minimal mouse interaction.
While development of the original Nylas Mail has been discontinued, the open source community has forked the project to continue improving and maintaining this powerful email solution, demonstrating the resilience and sustainability inherent in open source software development.
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5. Mailspring
Mailspring represents a more modern approach to open source email clients, offering a sleek, contemporary interface while maintaining the transparency and community benefits of open source development.
Built on Electron, Mailspring provides a consistent experience across Windows, macOS, and Linux platforms.
The client features an impressive array of productivity tools, including send later functionality, read receipts, link tracking, and quick reply templates.
Mailspring’s unified inbox presents a streamlined view of multiple accounts, while its conversation view organizes emails into logical threads for easier following of discussions.
The application includes powerful search capabilities that index the full text of messages for lightning-fast results.
Mailspring’s composer includes rich formatting options, easy file attachments, and inline image support.
While the core application is fully open source, Mailspring offers a premium tier with additional features such as advanced tracking and enhanced productivity tools, providing a sustainable development model while keeping essential functionality free and open.
The client’s focus on user experience and modern design makes it particularly appealing to users transitioning from proprietary email solutions.
6. Claws Mail
Claws Mail emphasizes speed and efficiency in a lightweight package that performs exceptionally well even on older hardware.
This GTK+-based client offers remarkable stability and quick operation across Linux, Windows, and BSD systems.
Claws Mail’s modular architecture allows users to extend functionality through plugins for calendar integration, RSS feeds, PDF viewing, and spam filtering without compromising the core application’s performance.
The client’s configuration options provide granular control over everything from interface appearance to networking parameters, appealing particularly to technical users who appreciate fine-tuned control.
Claws Mail features robust support for POP3, IMAP, and SMTP protocols along with SSL/TLS encryption for secure communications.
While its interface might appear utilitarian compared to more visually polished alternatives, this design philosophy contributes to the client’s exceptional performance and reliability.
The application’s powerful filtering system and search capabilities make managing large email archives straightforward, allowing users to quickly locate specific messages based on various criteria.
Explore: Tuta vs Protonmail
7. Evolution
Evolution delivers a complete personal information management solution that extends beyond email to include calendar functions, contact organization, and task management.
Originally developed for GNOME desktop environments, this client has become a staple for many Linux users while also offering Windows compatibility.
Evolution’s integration with corporate email systems, particularly Microsoft Exchange servers through its Evolution Exchange connector, makes it an excellent choice for organizations transitioning to open source solutions.
The client features robust encryption options, including OpenPGP and S/MIME support, ensuring secure communication channels for sensitive information.
Evolution’s unified inbox allows users to manage multiple accounts seamlessly, while its powerful filtering capabilities help organize incoming messages according to user-defined rules.
The application’s clean, intuitive interface strikes a balance between functionality and accessibility, making it suitable for both casual users and power users requiring advanced features.
Evolution’s search functionality deserves special mention, offering lightning-fast results even when navigating large email archives.
8. Sylpheed
Sylpheed delivers a streamlined email experience focused on simplicity, security, and efficiency.
This lightweight client runs smoothly on minimal hardware, making it ideal for older computers or systems with limited resources.
Despite its small footprint, Sylpheed supports essential features including multiple accounts, filtering, and search capabilities.
The client emphasizes security with built-in support for GnuPG encryption and SSL/TLS connections.
Sylpheed’s interface follows a traditional three-pane layout with folders, message list, and content views arranged for intuitive navigation.
The application supports junk mail filtering to help manage unwanted messages, along with customizable templates for frequently used responses.
Sylpheed’s development philosophy prioritizes stability and reliability over feature bloat, resulting in an application that performs consistently across Linux, Windows, and other platforms.
While lacking some of the visual polish and advanced features of larger clients, Sylpheed’s focused approach to email management appeals to users seeking a straightforward, dependable solution for their communication needs.
Explore: Protonmail Review
9. Geary
Geary brings a refreshingly minimalist approach to email management with a clean, conversation-focused interface designed specifically for GNOME desktop environments.
This lightweight client emphasizes usability and simplicity while still offering essential features for effective email handling.
Geary’s conversation view presents emails as threaded discussions, making it easier to follow complex exchanges without losing context.
The client supports multiple accounts with a unified inbox option, quick search capabilities, and seamless integration with desktop notifications.
Geary’s composers provides a distraction-free writing environment with support for basic formatting and attachments, staying true to its philosophy of focused simplicity.
The application’s startup time and message loading speeds are notably fast, making it ideal for users who frequently check their email throughout the day.
While Geary intentionally avoids overwhelming users with configuration options, its thoughtful defaults and intuitive design make it immediately productive for most email tasks.
The client’s development team continues to refine the balance between essential functionality and interface simplicity, making Geary particularly appealing to users who value streamlined, distraction-free tools.
10. Trojitá
Trojitá stands out for its exceptional handling of IMAP email accounts, using innovative technical approaches to deliver remarkable speed and efficiency.
Developed primarily for the Qt platform, this open source client employs on-demand message loading and network request batching to minimize bandwidth usage and maximize performance, making it particularly valuable for users with limited connectivity or large mailboxes.
Trojitá’s interface follows a logical multi-column layout that adapts well to different screen sizes, from desktop monitors to smaller tablet displays.
The client excels at offline operations, intelligently synchronizing when connectivity becomes available without requiring user intervention.
Trojitá includes powerful search capabilities that leverage IMAP server-side searching when available, resulting in extremely fast results even across large message archives.
While primarily focused on IMAP protocol support, the client handles this specific use case with exceptional attention to technical details and performance optimization.
Trojitá’s clean codebase and focused development approach have made it a foundation for other email projects seeking reliable IMAP handling, demonstrating how specialized open source tools can excel by perfecting specific functionality rather than attempting to cover all possible use cases.
11. Rainloop
Rainloop distinguishes itself as a browser-based open source email client that users can install on their own servers, combining webmail convenience with self-hosting privacy benefits.
This PHP-based solution features a clean, responsive interface accessible from any modern browser across desktop and mobile devices.
Rainloop supports multiple email accounts with unified inbox functionality, featuring drag-and-drop operations for message management and file attachments.
The client includes conversation threading, contact management, and calendar integration, covering all essential personal information management needs in a web-based environment.
Rainloop’s security features include two-factor authentication and encryption options, while its plugin architecture allows for customization and extension beyond core functionality.
The application’s responsive design adapts seamlessly to different screen sizes, providing consistent usability across devices without requiring separate applications.
Rainloop’s self-hosting model gives organizations and individuals complete control over their email interface without relying on third-party services, making it particularly valuable for privacy-conscious users who still want the accessibility of web-based email.
The client’s active community continues to enhance security features and usability, making Rainloop a mature option for those seeking a self-hosted email solution.
Also Read: The Ultimate Gmail Review
12. Balsa
Balsa offers a mature, dependable email client built for the GNOME desktop environment with a focus on accessibility and standards compliance.
This lightweight application provides a familiar three-pane interface with folders, message lists, and content views arranged for efficient navigation.
Balsa includes multi-account support with customizable sending and receiving options for each account, along with flexible filtering capabilities for organizing incoming messages.
The client features built-in support for GPG encryption, enabling secure communication directly within the application without requiring external plugins.
Balsa’s MIME handling includes proper display of various content types and attachments, while its composer supports both plain text and formatted messages.
The application’s strong accessibility features, including keyboard navigation and screen reader compatibility, make it particularly valuable for users with specific accessibility requirements.
Balsa’s development history spans decades, resulting in a stable, reliable application with well-tested code and consistent behavior.
While primarily designed for Linux environments, Balsa exemplifies the open source ethos of creating software that works reliably without unnecessary complexity or resource demands, appealing to users who prioritize stability and predictable behavior in their email tools.
Conclusion
Open source email clients represent more than just alternatives to proprietary software.
They embody a philosophy of user control, transparency, and community collaboration.
Each of the clients discussed offers unique strengths, whether in security features, interface design, cross-platform compatibility, or resource efficiency. The beauty of open source solutions lies in their adaptability.
Users can choose clients that align with their specific requirements and values, or even contribute to their development.
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Do Email Clients Really Matter?
Email is a stand-alone communication mode for any business. However, having multiple accounts and managing them on different platforms consumes precious money.
Got confused?
Time is Money, Right?
Here comes the advantage of open source email client that organizes emails and keep your inbox sorted through a single user interface. These email clients windows save a lot of time for businesses (in other terms, gains you profits). So, it has become the need of the hour to pick the best email software to boost your productivity.Let’s get into some depth about email clients.
Introduction
Although technology is advancing, many people still use emails for professional communications. They made the formal interactions seem simplified and accessible. It will be quite challenging to communicate inside and outside the organizations without the help of emails. It is necessary to use email for effective interaction because it acts as a secure medium for transmitting data. So an open source email client allows enterprises and users to set up a secure and safe interaction.
You know that Open Source Desktop Email Clients play an important role in the effective communication. Specific characteristics they possess make them easy to utilize and reliable.
- Email clients offer a platform to make companies interact with their users efficiently. They also offer internal communication within a certain organization.
- They utilize strong encryption keys and complicated algorithms to make secure and safe data transmission.
- Using them, you can enhance your company’s work efficiency and productivity.
So,elevate your small businesses with one of today’s popular open source desktop email clients mentioned here.
All email clients render almost the same features, but some of them come with additional features.
Read on to Know More About Best Free Email Clients
1. Thunderbird:
It is available for Windows, Mac, and Linux. Thunderbird is the only free and open source mail clients that is viable for everyday personal use. If you don’t want to go for a premium in your lifetime, it is the best option. Linux users get the maximum benefit out of this email client.
Features
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No clunky interface, glitchy performance, and lack of advanced features!.
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You can have add-ons, extensions, and plug-ins within this single interface.
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Attachments: No need to bother about the huge stack of files as this sends bulk amounts of attachments without any hassles.
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Integrations include Manoderecha, RadioGNU protocol, Cardbook, and TbSync.
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Customized Interface: This Open Source Desktop Email Clients customized interface lets you change the way of the view of email as you want.
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Autorespond:This open source email client feature provides a reply automatically thus saves time.
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Message Filters: You can have advanced filters that
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Avatars: This feature lets you download this app at ease.
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Read and Send Receipts: It lets you confirm on emails whether they were delivered/read or not.
2. Evolution:
It is a personal information management application that offers calendars, address books, task list functionality, and integrated mail. Evolution is an open-source email client that supports different network protocols and industry-standard data formats for exchanging information. It can integrate with Microsoft Exchange smoothly. It also operates well with Gmail too.
Features
- Calendar view: This email client has a built-in calendar view. It is to have clarity about the overview of your information over time.
Calendar integration allows you to synchronize your events and tasks with the calendar app. - Multiple account support: It supports various accounts without needing to log in and log out.
- Ad-free: It doesn’t have any type of external advertising.
- GPG Encryption: Evolution supports GnuPG(GPG) for encrypting messages, files, emails etc.
- Reminders: It lets you set reminders for events, actions, and tasks depending on time, condition, or place parameters.
Sync with Google Calendar: You can synchronize the evolution email client with Google Calendar. - Spam Filter: It can detect unwanted, virus-infected, unsolicited calls, files, emails etc.
3. Claws Mail:
It is another best open-source email client software for Fedora, Debian, Ubuntu, FreeBSD, and Windows. It is a fast and user-friendly email client through which you can do every task that is email related. It is utilised to maintain your multiple email account emails. You can produce various accounts and configure claws-mail with your email service. For this, you can use the configuration tab. After configuration, use the Get Mail option to acquire all your email accounts in one place.
Features
- Message: It enables you to pick whether you wish to receive messages from all your accounts or your current account. It will also allow you to compose email messages, forward the email, reply to emails, move emails to trash, and forward attachments etc.
- Side Tools Panel: You can access your inbox, drafts, sent mail folder, trash etc., from the side tools panel.
- Filters: You can filter your emails based on parameters like keywords, date, etc.
- View: It is the best feature that is handy and allows you to alter this software look. It provides features such as thread view, fullscreen, hide all threads, show all headers, and expand all threads etc.
- Offline Mode: You can disconnect this email client from the internet and use it offline. It also stops the synchronization between the email service provider and the client.
4. Sylpheed:
It is another open source mail client software for Unix, BSD, Linux, and Windows. It is lightweight and simple that you can get with a dated user interface. It doesn’t support any email having graphics. But you can find significant management features like Address Book, Email Tools Panel, Mailbox support etc.
Features
- Address book: This email client’s address book helps you manage, store, and retrieve your contacts.
- Email Tools Panel: You can access your sent mail, inbox, junk mail, and trash from this panel.
- Inbox: You can use the inbox feature to pick from which account you wish to receive emails and messages. It also offers you options for replying to emails, composing mail, and forward emails.
- View: It helps you optimize the email layout based on your requirements using thread view, collapse threads, expand all threads, separate folder trees etc.
- Get All option: You can receive all your emails from every account in one place.
- Delete duplicate messages: It is the best feature through which you can find and eliminate all the duplicated messages.
5. MailSpring:
It is a desktop best email client mainly designed by Windows 10, Linux, and macOS High Sierra. It has modern characteristics like snoozing, templates, offline, search, inbox, and support for the labels of Gmail. It is free and supports every IMAP provider, including iCloud, Gmail, and Office 365. It also has a pro version with many features: contact profiles, read receipts, link tracking, etc.
Features
- Dark Mode: It supports dark mode for convenient usage in low-light conditions.
- Unified Inbox: View emails from every account in one unified view with this email client.
- Support to multiple accounts: It supports various accounts without logging out and logging in.
- Theme support: You can utilize templates and themes to change the look and feel of this open-source email client.
- Email Organizer: It enables you to take control of your unified inbox by using controlling and filtering tools.
- Extensible by Plugins/ Extensions: It can be extended with extensions, plugins, and add-ons.
6. KMail:
It is a state-of-the-art open-source email client windows which integrates well with widely utilized email providers like Gmail. It offers various features and tools for maximizing your productivity. It makes it easy and fast for you to work with large email accounts. KMail greatly supports different email protocols like Microsoft Exchange, POP3, IMAP etc.
Features
- Secure default settings: It provides specific default settings for great end-to-end encryption support, safeguarding your privacy, and detecting spam.
- Integration: The meeting invitations can be added easily in the form of events into address auto-completion, KOrganizer, crypto preferences, avatars etc., that are loaded from KAddressBook.
- Standard Compliant: It supports standard push email, mail protocols, jnline OpenPGP, server site filtering, S/MIME, and PGP/MIME.
- Other powerful features: It also has many features, which include multiple sender identities, offline support, powerful filtering, searching, multiple language support, mailing list management, tagging functionality, and flexible configuration.
7. Spike:
Spike is a cloud-based email client that is available for Windows 10, macOS, iOS, and Android. It’s rich-feature set include:
Features
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Built-in Group Chat: No need to ping a single message in this open source email clients windows to multiple people of your team instead you can have a group chat that speeds up the workflow. Even the people who don’t use Spike can join the group.
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You can connect all your Gmail, Yahoo, iCloud, Hotmail, Office/Outlook 365, GoDaddy email, AOL, IONOS mail, Exchange, and all IMAP mail accounts to Spike’s unified inbox.
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Calendar, Notes, Task: Create tasks, events, or appointments and add notes to them for more productive email management.
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Advanced Search: This open source email client lets you find any file in a blink of an eye.
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Video and Audio Calls: This feature lets you connect with your team/clients via audio/video calls.
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Real-Time Messaging: read receipts, send later, undo send, snooze are the basic features that streamline the way of emails. You can include multi-media to emails. You can also use translate, text-to-speech, and voice notes for better email management.
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Priority Inbox: It lets you concentrate on important mails by sending other unimportant messages and newsletters into another inbox.
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File Preview: You can view the content of a file without opening or downloading it.
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Reminders: This open source email client feature alerts you on incoming emails and to-do lists.
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Instant Unsubscribe: It enables you to unsubscribe from unnecessary promotional emails and other subscribed newsletters in a fly.
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Email Encryption: It lets your confidential data, attachments, and emails even more confidential.
8. Mailtrim:
Mailtrim is the best free email client that works for all desktops-Mac, Windows, and Linux. It is a perfect tool for both small businesses and big giants.This open source email can support IMAP and POP3 servers. The features that vie anybody’s attention are.
Features
- Great UI: This open source email client is designed with simple and stylish icons and a good layout that fits the monitor of any size. Hence, it can be accessed at ease and quickly.
- Clutter-free inbox: No restrictions on the number of accounts. It lets you manage multiple email accounts within a single inbox and classify them separately for quick access. You can access all contacts in this single interface as well.
- Integrations: Cloud storage apps like Google Drive and Dropbox and CRM that enables you to build a strong and long-term relationship with your clients are integrated into this application.
- Excellent E-mailing: You can label emails with a flag, add a note, and schedule emails. You can create signatures that will be added directly while composing a message. The advanced filters let you find out the required file wherever it is.
- Preview: You can preview emails, images, and documents without opening them through this Open Source Desktop Email Clients.
- Advanced Search: This feature lets you retrieve the required mails in a fraction of seconds. No need to go through the entire inbox.
- Security: PGP support makes emails more secure and confidential.
- Respond later: This reminds you of important emails that need to be replied in due time.
- Customization: Display, reminders, and interface can be customizable as per your preferences.
- EventCalendar: It lets you schedule emails with notes, highlights, and colors and get notified on the same.
9. eM Client:
It is another desktop email client that is available for Windows and Mac OS and compatible with multiple mail servers. This email client open source comes with full support for all email services like Hotmail, Gmail, Yahoo, etc. and also with RSS feed support.
Features
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Message encryption: This open source email client feature enables more security to your most confidential emails.
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Calendar and Tasks: You can customize various views and interface, send invitations, and get reminders for all.
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Contacts organization: Contacts can be synchronized with Gmail, Exchange, iCloud, Office 365, and Outlook. Users can view and manage communication and attachment history for each contact.
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Advanced search and filters: These features in this Open Source Desktop Email Clients let you retrieve the exact email or attachment that you want.
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Templates & Signatures: eM Client has a wide variety of email templates to design appealing emails and you can add signatures so that you need not to sign each time you compose a mail.
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Conversation view: With this feature, all the messages are grouped automatically for easy access.
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Integration: Chat services like Facebook, Google Talk, and Jabber. Thus, it is considered as an instant messenger.
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Backup: All the data can be backed up when you need it. YOU no need have the fear of loss of important mail threads.
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Spell Checker: Just go on writing. The spell checker will let you know when there are grammatical errors.
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Offline Access: You can manage emails even in offline through this open source email client.
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Message Encryption: You can sendPGP or S/MIME encrypted emails easily.
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Premium features include unlimited email accounts, Email translator, VIP support, and Access to the license manager.
10. Mailbird:
This free open source mail client for PC provides you multiple accounts support and other additional features that make email management more hassle-free. This is the reason why it is it is considered as the best open-source email client in the healthcare industry, specially by ehr solutions providers.
Features
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Contacts Manager: You can merge contacts, create groups, customize interface, themes, and signatures), and use various shortcuts to compose emails and manage them quickly.
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Customized layout and free themes allow you to customize the view you want.
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App integration: Mailbird, the open source email client is integrated with storage apps such as Dropbox, Google docs, and Degoo; social apps like Facebook, WhatsApp, Twitter; chat and video conferencing tools like Slack, Asana; task manager tools like Todoist, Trello, moo.do; and Google and kin calendar.
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Messaging: You can send, unsend, receive, and filter emails. Besides, you can give in-line replies for more clarity.
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Offline Access: Using this open source email client windows, You can organize emails even in offline in this Open Source Desktop Email Clients.
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Multi-lingual support: It supports around 21 languages.
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Snooze: You can postpone a reply by snoozing messages lateras per the priority of the email.
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Attachment Features: You can attach emails by simply a drag and drop. Also, you can get attachment reminders and the attachment search retrieves you the exact file that you want.
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Customer Support: Users of Mailbird will have all-around technical support from the
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Premium Features: If you want to use it commercially, go for the premium. Unlimited email accounts setup, Snooze email feature, email speed reader, attachment quick preview, Linkedin Lookup, and custom sounds are its features that manage emails even smarter.
Wrapping Up:
The open source desktop email clients can push your business ahead of competitors by streamlining your workflow. So, here are the best 5 open source desktop email clients that help you in organizing your emails which saves time. Many Startups and big businesses mainly use these email clients. So, sort out your inbox using a single user interface and arrange your emails without the confusion of finding them by utilizing any of the best open-source email clients.
FAQ’s
Which mail client is open-source?
Mozilla Thunderbird is a more popular open source email client than other email clients. It has many features with various supporting plugins like theming, management of large files, and calendar support.
What email software that is an OSS?
Tutanota is the safe and secure open source alternative to Gmail and Co with a complete focus on privacy, ease of use, and Security.
Does Google have a desktop email client?
Google doesn’t have any desktop email client for Gmail. So the users are stuck utilising internet browser windows as it’s the only route to access the Gmail account.
Nylas Mail — the open-source, extensible mail client
Nylas Mail was an open-source mail client built on the modern web with Electron, React, and Flux. It was designed to be easy to extend, and many third-party plugins are available that add functionality to the client.
⚠️ Nylas Mail was initially released and open-sourced in early 2015 and was maintained by Nylas until Spring 2017. While Nylas no longer supports Nylas Mail, you can download the latest release or build it from source. There are also several forks that are being actively developed and maintained.
Getting Started
Setup your Environment (Mac):
- Install Homebrew
- Install NVM & Redis
brew install nvm redis
- Install Node 6 via NVM:
nvm install 6
npm install
Setup your Environment (Linux — Debian/Ubuntu):
- Install Node 6+ via NodeSource (trusted):
curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
sudo apt-get install -y nodejs
- Install Redis locally
sudo apt-get install -y redis-server redis-tools
benefit of letting us use subdomains. npm install
Running Nylas Mail
npm run client
: Starts the appnpm run test-client
: Run the testsnpm run lint-client
: Lint the source (ESLint + Coffeelint + LESSLint)
Exploring the Source
This repository contains the full source code to the Nylas Mail client and it’s backend services. It is divided into the following packages:
- Isomorphic Core: Shared code across local client and cloud servers
- Client App: The main Electron app for Nylas Mail
mirrored to open source repo. - Client Sync: The local mailsync engine integreated in Nylas Mail
- Client Private Plugins: Private Nylas Mail plugins (like SFDC)
- Cloud API: The cloud-based auth and metadata APIs for N1
- Cloud Core: Shared code used in all remote cloud services
- Cloud Workers: Cloud workers for services like send later
See /packages
for the separate pieces. Each folder in /packages
is
designed to be its own stand-alone repository. They are all bundled here
for the ease of source control management.
Digging Deeper
In early 2016, the Nylas Mail team wrote extensive documentation for the app that was intended for plugin developers. This documentation lives on GitHub Pages and offers a great overview of the app’s architecture and important classes. Here are some good places to get started:
- Application Architecture
- Debugging Nylas Mail
The team has also given conference talks and published blog posts about the client:
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ReactEurope: How React & Flux Turn Apps Into Extensible Platforms
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ForwardJS: Electron, React & Pixel Perfect Experiences
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Blog: Splitting from Atom
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Blog: Building Plugins for React Apps
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Blog: Nylas Mail Build Process
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Blog: Low level Electron Debugging
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Blog: A New Search Parser
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Blog: Developers Guide to Emoji
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Blog: Nylas Pro
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Blog: Nylas Mail & PGP
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Blog: Calendar Events and RRULEs
Running the Cloud
When you download and build Nylas Mail from source it runs without its cloud components. The concept of a «Nylas ID» / subscription has been removed, and plugins that require server-side processing are disabled by default. (Plugins like Snooze, Send Later, etc.)
In order to use these plugins and get the full Nylas Mail experience, you need to deploy the backend infrastructure located in the cloud-*
packages. Deploying these services is challenging because they are implemented as microservices and designed to be run at enterprise scale with Redis, Postgres, etc. Because these backend services must access your email account, it is also important to use security best-practices (at the very least, SSL, encryption at rest, and a partitioned VPC). For more information about building and deploying this part of the stack, check out the cloud-core README.
Themes
The Nylas Mail user interface is styled using CSS, which means it’s easy to modify and extend. Nylas Mail comes stock with a few beautiful themes, and there are many more which have been built by community developers
Bundled Themes
- Dark
- Darkside (designed by Jamie Wilson)
- Taiga (designed by Noah Buscher)
- Ubuntu (designed by Ahmed Elhanafy)
- Less Is More (designed by Alexander Adkins)
Community Themes
ToogaBooga | Material | Monokai |
Agapanthus—Inbox-inspired theme | Stripe | Kleinstein—Hides account sidebar |
Arc Dark | Solarized Dark | Darkish |
Predawn | Ido—Polymail-inspired theme | Berend |
ElementaryOS | LevelUp | Sunrise |
BoraBora | Honeyduke | Snow |
Hull | Express | DarkSoda |
Bemind | Dracula | MouseEatsCat |
Sublime Dark | Firefox | Gmail |
To install community themes:
- Download and unzip the repo
- In Nylas Mail, select
Developer > Install a Package Manually...
- Navigate to where you downloaded the theme and select the root folder. The theme is copied into the
~/.nylas-mail
folder for your convinence - Select
Change Theme...
from the top level menu, and you’ll see the newly installed theme. That’s it!
Want to dive in more? Try creating your own theme!
Plugins
Some plugins come pre-installed, and are a great starting points for creating your own:
- Translate—Works with 10 languages
- Quick Replies—Send emails faster with templates
- Emoji Keyboard—Insert emoji by typing a colon (:) followed by the name of an emoji symbol
- GitHub Sidebar Info
- View on GitHub
- Personal Level Indicators
- Phishing Detection
Community Plugins
Note these are not tested or officially supported by Nylas, but we still think they are really cool! If you find bugs with them, please open GitHub issues on their individual project pages, not the Nylas Mail (N1) repo page. Thanks!
Jiffy—Insert animated GIFs | Weather | Todoist |
Unsubscribe | Squirt Speed Reader | Website Launcher—Opens a URL in separate window |
Cypher—PGP Encryption | Avatars | Events Calendar (WIP) |
Mail in Chat (WIP) | Evernote | Wunderlist |
Participants Display | GitHub |
When you install packages, they’re moved to ~/.nylas-mail/packages, and Nylas Mail runs apm install on the command line to fetch dependencies listed in the package’s package.json
Forks
There are several forks of Nylas Mail that you should check out. If you’re just learning about Nylas Mail, it is highly recommended you use one of these instead.
- Mailspring — Significant rewrite by one of the original authors focused on performance and cloud plugins
- Nylas Mail Lives — Community effort to fix bugs and improve the client! (Seeking Maintainers)