Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
Altarsoft PDF Reader - Altarsoft PDF Reader is a simple to use PDF files management program that allows its users to view PDF files, encrypt the files and even annotate these files as well.
The Bat - The Bat! is a secure desktop email client for Windows, designed to protect your correspondence against third-parties and to save your time.
eXPert PDF Reader - eXPert PDF Reader is a free to use PDF reader and views for the Windows operating systems.
Geary - Geary is an email application built for GNOME 3.
Cool PDF Reader - Just like its name Cool PDF Reader, this small PDF reader is a really a cool PDF reader for viewing, reading and editing PDF files for free.