Lotus Traveler Issue

Recently a couple of our clients added iPhones to replace their Blackberries in their operation and we installed Traveler for them so that they can access there mail and calendar from their iPhones. Everything is working fine with the one exception. Using BES with your Blackberry you have the option of whether the handheld or the desktop has control on the deletion of messages. So if you set it to the desktop (default) when the user deletes the message from their Blackberry to remove the clutter of messages, the messages remain in their mail file until they delete it using their Notes or iNotes client. This is very handy. However, with the Traveler Exchange ActiveSync there does not seem to be a similar option. Has anyone encountered this issue and found a resolution?