ONLYOFFICE - ONLYOFFICE is a complete office and productivity suite.
Mailspring - Mailspring is a mail client for Mac, Windows and Linux.
LibreOffice - Free office suite, open source, and compatible with .doc, .docx, .xls, .xlsx, .ppt, .pptx files. Updated regularly – download for free. Originally based on OpenOffice.org.
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
WPS Office - Would you need Office Word, Excel or PowerPoint for Home, business or School? WPS.com would give you right version for you.
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.