Alternatives to Nextcloud Mail for all platforms with any license

Thunderbird

Thunderbird is a free, open source, cross-platform e-mail, news and instant messaging client. The project strategy is modeled after Mozilla Firefox.

Free Open Source Mac Windows Linux BSD PortableApps.com ... Haiku
Extensible by Plugins/Extensions Built-in RSS reader Built-in Calendar Calendar integration ... Categories Customizable Extensible by Plugins/Extensions Free API Gmail integration Google Calendar integration Import from Google Reader Support for IMAP Integrated Chat Integrated Web Browser Legacy addons support Multiple Account support Export to OPML Import feeds from OPML POP3 Support Portable Secure file sharing SMTP integration Tabbed interface Support for Themes Add a feature

1766 Like
Microsoft Office Outlook

Part of the Microsoft Office Suite, Outlook is a personal information manager that lets you manage your e-mail, calendar, contacts, and tasks.

Commercial Mac OS X Windows Web Android iPhone ... Android Tablet Windows Phone iPad Apple Watch Android Wear
Built-in Calendar Dark theme Signature with image Add a feature

312 Like
Evolution

Evolution is the official personal information manager and workgroup information management tool for GNOME. It combines e-mail, calendar, address book, and task list...

Free Open Source Linux BSD S/MIME GNOME OpenPGP
Built-in RSS reader CalDAV Calendar integration CardDAV ... Encrypted email Integrated Spam Protection Multiple languages POP3 Support Add a feature

150 Like
Mailbird

Mailbird is more than just another email client - It's an all-in-one communication platform for email, contacts, calendar, apps, task management, video meetings and...

Freemium $ $ $ Windows
Undo send Asana integration Sync Contacts Conversation view ... Dropbox integration Facebook integration GSuite Integration Multiple Account support Slack integration Trello integration Twitter integration Unified inbox Add a feature

270 Like
Postbox

Postbox is an email application that helps you organize your work life and get stuff done. It has all the elegance and simplicity of Apple Mail, but with more power...

Commercial Mac Windows
Multiple Account support Box.com integration Built-in RSS reader Dropbox integration ... Extensible by Plugins/Extensions Support for IMAP Multiple languages Onedrive integration POP3 Support Tabbed interface Visual Programming Add a feature

130 Like
Claws Mail

Claws Mail is an email client (and news reader), based on GTK+, featuring Quick response Graceful, and sophisticated interface Easy configuration...

Free Open Source Windows Linux BSD
Lightweight Built-in RSS reader Content Filtering Customizable ... Extensible by Plugins/Extensions Support for IMAP Multiple languages Multiple Account support Add a feature

76 Like
Geary

Geary is an email application built for GNOME 3. It allows you to read and send email with a simple, modern interface.

Free Open Source Linux BSD GNOME
No features added Add a feature

70 Like
Opera Mail

Opera Mail powerfully organizes, indexes, and sorts your messages. It has spam filtering (both automated and Bayesian), supports POP3 and IMAP, newsgroups as well as...

Free Mac Windows PortableApps.com
Built-in RSS reader Integrated Spam Protection Message Filtering Portable Add a feature

96 Like
- Discontinued Opera Mail is no longer updated and supported, but last version, 1.0.1044, released in February 2016, can be still downloaded from the official website.
Mutt

Mutt is a small but very powerful text-based mail client for Unix operating systems. Some of its features are: color support, message threading, MIME support (including...

Free Open Source Mac OS X Windows Linux Xfce
Command line interface Support for IMAP POP3 Support S/MIME support Add a feature

51 Like
Airmail

Airmail is a lightweight and lightning fast mail client for Mac. Feature list: Accounts: - Unified Inbox and folders - Multi Account with editable html...

Commercial Mac OS X iPhone iPad Apple Watch
Customizable Dropbox integration Fullscreen support Lightweight ... Multiple Account support Add a feature

59 Like
Sylpheed

Sylpheed is a simple, lightweight but featureful, and easy-to-use e-mail client (mailer, MUA). Sylpheed runs on many systems such as Windows, Linux, BSD, Mac OS X and...

Free Open Source Mac OS X Windows Linux BSD PortableApps.com
Lightweight Add a feature

51 Like
Kontact - KMail

KMail is the email component of Kontact, the integrated personal information manager of KDE. Kontact is a personal information manager and groupware software suite for...

Free Open Source Mac OS X Windows Linux BSD
No features added Add a feature

32 Like
The Bat

The Bat! is a secure email client software, built to protect your correspondence against third-parties. .

Commercial Windows S/MIME OpenPGP
Built-in RSS reader Support for IMAP POP3 Support Portable Add a feature

46 Like
Microsoft Mail and Calendar

Windows 10 has Mail and Calendar apps already built in. With the Mail application you can now easily see all message from your...

Free Windows Windows S
Email tracking Bundled with Windows Add a feature

19 Like
Canary Mail

Canary is an exciting new email client for Mac that offers a full set of powerful features with one key difference - your emails are not stored on a 3rd party server. ...

Commercial Mac OS X iPhone
No features added Add a feature

10 Like