On 9.1.2012, at 16.41, Tom Clark wrote:

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).

You can delete dovecot.index* and dovecot-uidlist files. Assuming you're using maildir.

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.

I doubt Courier would do that without deleting courierimapuiddb.