I like how FAST to configure it's really fast and easy to use

MailEnable is an advance mail administrator that covers the basic features (POP, SMTP, IMAP) of this type of software and with the paid services you have advanced capabilities. Some of the advanced capabilities you can find: Cloud Storage (WebDAV Support), Server Storage, SMS Connector, XCLIENT SMTP Extension, LDAP Service, Mobile Web Administration.

Ease of use is good with this. Very functional to see multiple things open on one screen without having to open/close tabs to see other information.