An easy addition for rule definition would be "Set Header To:" where Header was a prefined email header (e.g. "EPIMHdr:"). This would make it easy to auto-tag email according to rule definition.
This would work nicely with my other suggestion for defining a log file showing which rule caused an email to be transferred to a folder. Instead of a log file this new rule option could be defined to record the rule name.
New Rule Option
Moderators: TerryRogers, Max