Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Facebook Messenger - Facebook Messenger is a faster way to message.
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.