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!
ONLYOFFICE - ONLYOFFICE is a complete office and productivity suite.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Apache OpenOffice - Apache OpenOffice is an open source, office document productivity suite.
eM Client - eM Client is a fully-featured email client for Windows and macOS with a clean and easy-to-use interface. eM Client also offers features for calendars, tasks, contacts, notes, and chat.