Thunderbird

K-9 Mail is a 100% free and open source email client for Android.

… with Thunderbird, a popular email client for PCs. This feature allows users to keep their emails, contacts …

Vote: 4.5/5 (90 votes) Platform: Android

A mail client for mobile devices that supports POP and IMAP email account types

PRO: Fits easily on a USB pen drive
CON: Synchronisation with mail server can be problematic
Vote: 4.7/10 (22 votes) Platform: Windows

Email interface that also offers news and chat

PRO: Lets users manage calendars seamlessly
CON: Some email clients aren’t supported
Vote: 7.2/10 (315 votes) Platform: Windows

Deleted emails can be restored and folders maintained in Mozilla Thunderbird with this Windows application

Vote: 10.0/10 (2 votes) Platform: Windows

A cross-platform calendar program based on Mozilla's XUL user interface language

PRO: Features add-ons
CON: Not updated very often
Vote: 8.3/10 (38 votes) Platform: Windows