I have someone in my office with a Curve 8530 from Verizon that when I delete an e-mail from Outlook, it doesn't delete on the device. I can do every other function, mark as read, mark as unread, accept calendar appointments, etc. But when you delete an e-mail from Outlook, it doesn't delete from the device.
I have the device set up to wireless sync, delete on mailbox and handheld, and to have the mailbox win for all conflicts.
I have gone as far as wiping the device completely, and also having his account wiped and recreated from the BES and it still will not update on the device. I have tested other devices in my environment (older curves) and it works with no problems.
