Nokia has released a new version of Mail for Exchange version 1.5 for Nokia E Series mobile devices (ROM image 1.610.04.02 or later). Unlike previous versions, this version will not install on N Series mobile devices. And you will need to uninstall any previous version of the application from your device before installing the new version.

New features of this version include (from the release notes)

-Configurable heartbeat interval
-Detailed admin logging
-Notification improvements for “new emails”
-Ability to set importance flag for sent messages
-Improved handling for IT Policy updates
-Support for “Send As” capability
-Support for Microsoft Exchange 2007
-Support for Microsoft Small Business Server (not sure why this is new as there should be no difference b/w Exchange installed on SBS and standalone Exchange)
-Support for F-Secure
-Support for Symantec

Download here