I'm using DoveCot 1.1.11 and the MailDir format for mailboxes.
When I use Manage Folders to set "Show To: address instead of From: ?" to "Yes", the setting doesn't stick (each time I edit the folder the setting reverts to "No"). Also, predictably, the setting doesn't have the desired effect.
Noticed this in versions 1.410 and 1.420 of Usermin.