Apple added the ability to mark mail with a follow up flag in iOS 5. This is a function that has been available in the Notes client for quite a while but has not been supported by the Apple device platform. If running Lotus Traveler 184.108.40.206 or later and Apple iOS5 or later releases, you will be able to sync follow up flags in both directions.
Follow up flags should not be confused with Reply or Forward flags. With Lotus Traveler 220.127.116.11 and later releases, Reply and Forward flags will sync from the device to server but still are unable to sync from the server down to the device due to ActiveSync protocol limitations.
For additional information see the Lotus Traveler 8.5.3 Product Documentation
Lotus Traveler 18.104.22.168 Product Documentation
Lotus Traveler Maintenance Information
Lotus Traveler 853 System Requirements