If your windows mobile or iPhone is stolen or lost, you can send it a command to wipe it's memory clear of any Exchange data:
- Open Outlook Web Access.
- Log on to the device owner's mailbox.
- Click Options.
- In the Navigation pane, select Mobile Devices.
- Select the ID of the device that you want to wipe and remove from the list.
- Click Wipe all data from device.
- Click OK.
- Click Remove Device from List.