7 Best Free Open Source Email Client Software For Windows

Here is a list of best free open source email client software for Windows. These desktop open source email clients are completely free and you can even download, access, and make changes to their source code without any restriction.

Using these email clients, you can quickly access and manage your emails on a particular email account. In most of these clients, you can even add multiple email accounts and access emails of all accounts from one software. The good thing about an email client is that you don’t need to log in every time to access your emails, unlike web email services. Plus, email clients store all your emails and messages locally, thus you can even use these clients in the absence of an active internet connection, However, you still need an active internet connection to get new fresh emails. In some of these email clients, you can also include different email services along with messaging services with ease.

In these open source email clients, you can find all the essential email features like compose emails, reply to emails, forward emails, inbox, outbox, sent emails, trash emails, etc. Plus, advanced search and filter features to quickly locate desired emails are also present in these software. Besides core emailing features, you also get Calendar (to create and view appointments, tasks, etc.), Address Book (to create and manage contacts of multiple users), View (to adjust the looks of these clients according to your needs), and more features in some software. These email clients also come with some useful additional features such as Password Manager, Browser, Offline Mode, etc. Go through the list to know more about these open source email clients.

My Favorite Open Source Email Client Software For Windows:

Mozilla Thunderbird is my favorite email client because it is feature-rich and still quite easy to use. It also offers some handy additional tools like Chat, Offline Mode, Add-Ons, etc.

You can also check out lists of best free Open Source XMPP Client, Open Source Calendar Software, and Open Source Code Editor software for Windows.

Mozilla Thunderbird

Mozilla Thunderbird is a free open source email client software for Windows. It is a popular email client software that comes with a simple interface and all necessary features. Plus, its multi-tab interface also helps a lot by letting you open Inbox, Calendar, Tasks, Schedules, and other sections at a time. In it, you can also maintain multiple email accounts and view emails of a specific email account or all email accounts at once. Like all other email clients, you also need to configure it with your email service to receive emails. It has many other important features which you can check below.

Main Features:

• Inbox: This email client provides all necessary email features under this Inbox tab. From this tab, you can access your emails and messages of all your accounts, view your drafts, view sent emails, along with trash and outbox emails. Plus, features to compose new emails, reply mail, and forward email are also provided by it.
• Search and Sort Emails: To find emails, this email client provides multiple search and sort features like Quick Filter (to filter emails based on contacts, tags, attachments, starred, etc.), Standard Search (to search mail by using a keyword or phrase), and Filter Search (it lets you only search the filtered emails).
• Open In Conversation: Through this feature, you can view emails between you and another specific user as threaded chat.
• Calendar: In it, you can view all your scheduled tasks and other associated information.
• Tasks: It lets you schedule any task on a particular date that you can later view in the internal Calender.

Additional Features:

• Chat: The email client comes with its inbuilt chat service that lets you chat with other users who also use this email client.
• Offline Mode: Use it to completely disconnect this open-source email client from the internet.
• Add-ons: This software also supports add-ons, and you can easily find and import add-ons to this software to improve the existing feature set.

Final Thoughts:

It is one of the best free open source email client software that offers all important email management features without making things complicated.

SeaMonkey

SeaMonkey is another free open source email client software for Windows, macOS, and Linux. This email client comes with all in one internet application suite. In it, you can find all essential email client functions like compose mail, inbox, draft, outbox, etc. Plus, it is also quite simple to use. The main problem with this software is its interface that looks quite dated. Still, it is is quite simple to operate and offers all standard email managing features. However, to use this client, you need to first configure the SMTP protocol with your existing email service to use it. Now, let’s take a look at the main features of this email client.

Main Features:

• Main Email Features: In the Main & Newsgroup section of this software, you can find all the essential email client features like Compose, Get Message, Inbox, Draft, Sent, Reply, Reply All, Mark, etc. Plus, an advanced search option along with a sorting feature is present in it through which you can locate any saved mail.
• Events and Tasks: Using it, you can create and schedule tasks and events. A side Event panel consisting of events and their scheduled dates is also present in it.
• Import: It allows you to import existing emails, calendars, address books, filters, and feed subscriptions  to this software
• Sync: If you already have a SeaMonkey account, then you can use it to quickly synchronize all the mails and other settings of another client with this one.

Additional Features:

• Browser: This software comes with an inbuilt web browser through which you can browse the internet with ease.
• Composer: Using it, you can create web pages and publish them on the internet.
• Password Manager: It lets you store and manage all your passwords from one place.
• User Profiles: It allows multiple users to maintain separate user profiles.

Final Thoughts:

It is another free open source email client software in which you can find all important email features along with many additional features.

Claws Mail

Claws Mail is yet another open source email client software for Windows, Ubuntu, Debian, Fedora, and FreeBSD. It is a user-friendly and fast email client through which you can easily perform all the email related tasks. This client can also be used to manage emails of your multiple email accounts. To create multiple accounts and configure this email client with your email service, you can use the Configuration tab of this software. After configuring this client properly, use the Get Mail option to immediately get emails of all your accounts in one place.

Main Features:

• Side Tools Panel: From the side tools panel, you can access your inbox, sent mails folder, drafts, trash, etc., of one or all your accounts.
• Message: It allows you to manually choose whether you want to receive messages from the current account or all your accounts. Besides this, it also lets you compose an email message, reply to emails, forward email, forward attachment, move emails to trash, etc.
• View: It is another handy feature that lets you modify the looks of this software. To do that, it offers features like fullscreen, thread view, expand all threads, hide all threads, show all headers, etc.
• Filters: Using it, you can filter your emails according to parameters like date, keywords, etc.

Additional Features:

• Offline Mode: By enabling this feature, you can completely disconnect this email client from the internet. People use this feature to completely stop the synchronization between the email client and email service provider.
• Import and Export Mbox files: In this email client, you can also import and export your message and emails in the form of Mbox files.

Final Thoughts:

It is a dedicated open source email client software that you can try if you need a simple email client with the ability to manage multiple email accounts.

Interlink

Interlink is the next free open source email client software for Windows and Linux. It is mainly a Mozilla sourced community-based Mail, RSS, and Newsgroup client. Through this client, you can manage multiple email accounts and access mails of multiple accounts in one place. In it, you also get a handy Import feature that lets you import all the settings, addresses, emails, calendars, and other data from other clients to this client. The interface of this client is also quite simple and you will not face any problem while using it. Now, let’s take a look at some of the main features of this software.

Main Features:

• Mail Tools Panel: In this panel, you get all essential tools through which you can create, view, and manage Inbox emails, drafted emails, sent mails, trash mails, etc. In the Inbox, you can also find other important features that let you mark important emails, search emails, add sender to contact list, add tags to mails, etc.
• Filter and Search: Using the filter feature, you can filter your emails based on starred, attachment, contacts, tags, etc. Through search, you can quickly find all the emails containing a specific word or phrase.
• Message: It is a tab through which you can compose new emails, reply to emails, forward emails, tag emails, archive emails, open emails, etc.
• View: Using it, you can adjust the layout, text encoding, zoom level, headers, etc., to modify the default look of this software.

Additional Features:

• Activity Manager: It keeps a record of all the current and previous activities happening in this client like the number of downloaded emails, synced emails, forwarded emails, etc.
• Add-ons Manager: In it, you can view and delete all the existing add-ons of this client. It also enables, you to add more add-ons to this software.
• Offline Mode: You can enable this mode if you want to completely disconnect this client from the internet without actually disabling the internet in your system.

Final thoughts:

It is another decent open source email client software through which you can easily perform email-related activities and manage multiple email accounts.

Zimbra

Zimbra is another one of open source email client software for Windows, macOS, and Linux. Through this client, you can easily compose emails, send emails, receive emails, manage emails, categorize emails in multiple categories, and manage multiple email accounts with ease. Plus, you can use this client in both online and offline modes that enable you to access all the locally stored emails in the absence of poor or no internet connection. Besides email management activities, you can also use it to schedule and track various events and tasks.

Main Features:

• Mail: The Mail section of this software contains all email associated tools and features like inbox, drafts, sent folder, compose emails, reply mails, outbox, trash, etc. Besides this, sorting and searching tools to find emails are also present in this section.
• Address Book: Using it, you can quickly add senders and their contact information to this address book. At any time, you can access any contact and send emails to him/her.
• Calendar: In it, you can create new appointments and view existing appointments along with tasks and events.
• Tasks: With its use, you can create new tasks and events and add detailed information about them. After making a task, you can schedule it. You can view the scheduled task and events from the Calendar section.

Additional Features:

• Local Folders: With its use, you can save emails and messages in a local folder of your software. Later, you can import more emails or export locally stored emails in WinRAR archive format.
• Offline Mode: It lets you manually disconnect this open-source email client from the internet.

Final thoughts:

It is a cleanly designed open source email client software through which you can perform various email-related activities without putting much effort.

Rambox

Rambox is yet another free open source email client software for Windows. Unlike other similar email clients, it does not offer its own set of features and interface, instead, it directly integrates and opens up the interface of your email service. And, at a time, you can open multiple email accounts of different email services (Gmail, Outlook, Openmail, Yandex Mail, etc.) together. Apart from emails, you can also include messaging services like Allo, HipChat, Telegram, etc., to this software.

Main Features:

• Services: In the services panel, you can find all email and messaging services that you can quickly add to this email client.
• Desktop Notifications: By configuring the desktop notifications, you can receive the notifications of all your emails on the desktop.
• View: It offers zoom and actual size feature through which you can adjust the view of this client as you want.

Additional Features:

• Developer Tools: Though developer tools, you can further adjust the style, properties, and performance of this software.

Final Thoughts:

This free open source email client software offers a unique environment in which you can combine and access multiple email services together.

Sylpheed

Sylpheed is one more open source email client software for Windows, Linux, BSD, macOS, and Unix. It is a simple and lightweight email client that comes with a dated user interface. Plus, it does not support emails with graphics which is another drawback of this software. However, you can find all essential email management features in it like Multiple Mailboxes Support, Address Book, Email Tools Panel, etc.

Main Features:

• Email Tools Panel: From this panel, you can access your inbox, sent mail, drafts, trash, junk, etc.
• Address Book: This book helps you store, manage, and retrieve all your contacts.
• Message: Using it, you can manually choose from which account you want to receive messages and emails. It also gives you options to compose mail, reply to emails, forward mails, etc.
• View: It helps you optimize the layout of emails according to your needs using thread view, expand all threads, collapse threads, separate folder tree, etc., options.
• Get All: Using it, you can receive all the emails of all your accounts in one place.

Additional Features:

• Import and Export Mail Data: Through this feature, you can import and export mail data in UNIX Mbox, EML, and DBX formats.
• Delete Duplicate Messages: It is a handy feature through which you can find and remove all the duplicate messages.

Limitations:

• The inability of this email client to support graphics in emails and dated interface are two of its main limitations.

Final Thoughts:

It is a straightforward open source email client software that anyone can use with ease.