[Dovecot] Resetting a UID

Hi,

We've got a client with a Blackberry that hass deleted his emails off his Blackberry device. The BES won't re-download the messages as it believes it has already downloaded them (apparently it matches on UID).

Is there any way of resetting a folder (and messages in the folder) UID? I know in courier you used to be able to touch the directory.

Thanks,

Tom Clark