Kerio Connect
Benefits of Kerio Connect include:
Great Iphone/Ipad integration
Push Email, Contacts, Calendar, and now Tasks see: Kerio Tasks IOS 5
Costs
Lower cost per user than exchange.
Cross Platform
Server install on Windows, Mac OSX and Linux.
Open Source Software
Built using open source software including:
Cyrus Imap, Spamassasin, Postfix,
Client Integration
Support for Outlook integration including Outlook 2011 for Mac
Webmail client, with Ajax (drag and drop), equivalent to Outlook Webaccess.
Supported protocols: SMTP,Activesync, POP3, POP3S, IMAP,IMAPS, http,https
Identity Management Support
Active Directory and Apple Open Directory Support.
Note for linux users: Kerio are yet to release their own directory server, it will allow integration with all their products.
Migration Tools
Kerio provides varios tools to migrate your emails to Kerio Connect
Admin Interface
Web based admin interface.
Security
Spam, Antivirus and Attachment filtering to keep your inbox clear.
Archiving and Backup
You can journal all emails in and out of your email server for archie purposes.
There is built in backup which can be scheduled.
There are many more features that I have not mentioned but there are also some limitations tou can see below.
Limitations
It would be nice to have a quarantine for spam so that you could catch false positives.
Outlook connector can be a little buggy on Remote Desktop, but it is getting better.
Kerio Connect