Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
CallApp - Free Caller ID & Call Blocker app that allows mobile users to block phone calls, identify calls, blacklist unwanted callers and much more.
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.
CallerSmart - CallerSmart is an application that is basically used for the purpose of looking up mystery phone numbers for free.