Docusaurus - Easy to maintain open source documentation websites
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
DocFX - A documentation generation tool for API reference and Markdown files!
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Cirrus Insight - Respond to Customers Faster and Update Salesforce from Your Inbox with Cirrus Insight. Start your free 14-Day trial today! No Credit Card Required.
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.