Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community
Mailbird - Mailbird is the best email client for Windows 7, 8 and 10
LiveAgent - LiveAgent is a fully-featured web-based live chat and help desk software. It harnesses the power of a universal inbox, real-time live chat, built-in call center, and a robust customer service portal. Start your free 1 month trial today!
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.