IceWarp Server now comes with a built-in SyncML server but also allows a Users IceWarp Server account to act like a SyncML Client (with some added value).
The following picture explains the concept here:

As you can see from the above diagram your user can synchronize multiple clients. The User Account Data within IceWarp Server can be accessed via Groupware, Webmail and Outlook (via the Merak Outlook Connector).