Thunderbird - Thunderbird is a free email application that's easy to set up and customize - and it's loaded with great features!
Trustwave Secure Email Gateway - Trustwave Secure Email Gateway helps protect your email environment against modern threats such as malware, ransomware and phishing, and helps prevent loss of sensitive corporate data.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Mimecast Secure Email Gateway - Prevent targeted email-borne attacks with Mimecast Secure Email Gateway for cloud-based anti-virus and anti-spam protection.
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.
Appriver - AppRiver is an email and web security company, develops SaaS-based anti-spam, hosted exchange, email encryption and web protection solutions.