Small in size, and uses very less system resources.Very secure – comes with advanced protection.One of the best part of Pegasus Mail client is that it works very well in LAN settings, and has special support for Novell NetWare LANs that allow it to operate intuitively and with almost no maintenance. It is very feature rich, and still easy to use. This is one integrated tool that includes email client, browser, feed reader, IRC Client, and HTML Editor. SeaMonkey is a free internet application suite from makers of Firefox and Thunderbird. Syncs Zimbra calendar with Yahoo and Gmail calendars.Native account setup support for Yahoo, Gmail, Hotmail, and AOL.Apart from that, it is extremely easy to configure your accounts in Zimbra Desktop. Unline any other free email client, it has one big advantage – yu can even check your Yahoo mail in Zimbra Desktop.

Good security features, and spam protection.Sync your calendar with Windows Live Calendar.It supports Hotmail, Gmail, Yahoo Plus, and many more. This is really good, and has good resemblance with Microsoft Outlook. This is a free email client from Microsoft, and is a part of Windows Live suite.

Best email clients for windows 8