The Best Open Source Microsoft Outlook AlternativesTop Email Clients & Calendar Apps like Microsoft Outlook in 2023
The best open source alternative to Microsoft Office Outlook is Thunderbird. If that doesn't suit you, our users have ranked more than 100 alternatives to Microsoft Office Outlook and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Microsoft Office Outlook are K-9 Mail, Evolution, Mailspring and FairEmail.
Microsoft Office Outlook alternatives are mainly Email Clients but may also be Calendar Apps or Todo List Managers. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of Microsoft Office Outlook.Thunderbird
Is this is a good alternative?YesNo- Free • Open Source
- Email Client
- Calendar App
93 Thunderbird alternatives- Mac
- Windows
- Linux
- BSD
- AppImageHub
- Snapcraft
- Flathub
- PortableApps.com
- Haiku
- Homebrew
- Chocolatey
Thunderbird is a free, open source, cross-platform e-mail, news and instant messaging client. The project strategy is modeled after Mozilla Firefox.
- - Thunderbird is the most popular Windows, Mac & Linux alternative to Microsoft Office Outlook.
- - Thunderbird is the most popular Open Source & free alternative to Microsoft Office Outlook.
Thunderbird Features
Comments about Thunderbird as a Alternative to Microsoft Office Outlook
Thunderbird is best that other application listed here and GUI is also nice
5I transitioned all ove my computers from Windows to Linux. I had 4 computers so I used four different distributions with different linux bases, Debian and Arch. Thunderbird worked perfectly. The email client is awesome, I think they should devote more development efforts to calender and task management integration.
2The interface is just impossible for many people to use.
13s0razI would rather Thunderbird over Outlook because it's open source.
0St YUDAIt can access email server just as outlook
1K-9 Mail
Is this is a good alternative?YesNo46 K-9 Mail alternatives- Free • Open Source
- Email Client
- Android
- Android Tablet
- F-Droid
K-9 is an open source email client for Android with multi-folder sync, email signatures, Bcc-to-self, return-address configuration, keyboard shortcuts, Exchange Support, message flagging, IMAP deletes, saving attachments, configurable notifications and more.
- - K-9 Mail is the most popular Android & Android Tablet alternative to Microsoft Office Outlook.
K-9 Mail Features
Comments about K-9 Mail as a Alternative to Microsoft Office Outlook
John FastmanNot the prettiest, but it's open source (trustworthy), free, privacy-respecting and very functional. My go-to Android email client. I cannot hesitate less in recommending it.
4Online_Purchases1Deletes e-mail from the server even when underground in NYC subway. Makes life so easy to delete e-mails while on the train When surfacing, K-9 syncs with the server and POOF....those unwanted e-mails are gone from the server.
1Evolution
Is this is a good alternative?YesNo- Free • Open Source
- Email Client
- Calendar App
83 Evolution alternatives- Linux
- BSD
- Flathub
- S/MIME
- GNOME
- OpenPGP
Evolution is a personal information management application that provides integrated mail, calendaring, address book and task list functionality. Evolution supports a wide range of industry standard data formats and network protocols for information exchange, with an emphasis on...
Evolution Features
Comments about Evolution as a Alternative to Microsoft Office Outlook
It runs on Linux and you still have content if you are offline.
1Fast and User friendly. Light-weight and classic menus really give a touch of old classic office 2003. Easy integration of mails especially exchange mails without facing any bottlenecks.
1This would be the best alternative, except that it requires the Gnome desktop, so users of other desktop environments need to look elsewhere.
-1I've found it better than thunderbird and it can work with exchange just with one free plugin
0Support for EWS allows me to connect to exchange and get all the benefits like contacts and calendar I wouldn't so easily get on Thunderbird. Also it nicely integrates with the built in Ubuntu calendar as well which is a big plus.
1Mailspring
Is this is a good alternative?YesNo- Freemium • Open Source
- Email Client
45 Mailspring alternatives- Mac
- Windows
- Linux
- Arch Linux
- Fedora
- Ubuntu
Boost your productivity and send better email with Mailspring, a beautiful, fast email client for Mac, Windows, and Linux. Mailspring is free to use and an optional pro version adds read receipts, send later, reminders and more.
Mailspring Features
Comments about Mailspring as a Alternative to Microsoft Office Outlook
PaulSince Thunderbird is still bloated and overcomplicated for me on Linux, I'm using Mailspring for the moment. It's good, the interface is nice and it has plenty of features.
0Speed of work, good connection to the mail server, speed search.
0Beautiful theme options with custom designed themes available. I tried thunderbird a few times but always came back to mailspring. I LOVE the "views" feature that shows you how many times an email was opened and if it was forwarded by the recipient!
0FairEmail
Is this is a good alternative?YesNo46 FairEmail alternatives- Freemium • Open Source
- Email Client
- Android
- Android Tablet
- F-Droid
FairEmail is a privacy-focused email client with a setup wizard that helpfully walks you through the steps to use it with any email provider. There are many privacy settings including encryption via OpenPGP and S/MIME and reformatted emails to avoid phishing.
FairEmail Features
Comments about FairEmail as a Alternative to Microsoft Office Outlook
Rasheedopen source, secure, regularly updated
1Geary
Is this is a good alternative?YesNo- Free • Open Source
- Email Client
52 Geary alternatives- Linux
- BSD
- Flathub
- GNOME
- Flatpak
Geary is an email application built around conversations, for the GNOME 3 desktop.
Geary Features
Comments about Geary as a Alternative to Microsoft Office Outlook
Beatiful frontend Stable working Advanced features
1Claws Mail
Is this is a good alternative?YesNo- Free • Open Source
- Email Client
- Calendar App
84 Claws Mail alternatives- Windows
- Linux
- BSD
Claws Mail is an email client (and news reader), based on GTK+, featuring
Quick response Graceful, and sophisticated interface Easy configuration, intuitive operation Abundant features Extensibility Robustness and stability.
Claws Mail Features
Comments about Claws Mail as a Alternative to Microsoft Office Outlook
Claws Mail is email only, does not have many of the features of Outlook. Displaying HTML mail is sketchy at best.
-2