Auto Reply Rule

So I have a Rule setup for a user that I just moved to a new postoffice. The rule is to auto-reply to any new message that comes in with the old email address (which is now a nickname within GroupWise) with a message telling what the new address is.

Seems like the rule only executes upon the first instance of a message. Example: if emails the old address, it executes the rule. If the same account sends a separate new message to the same old address, the rule is not executed. Is this by design? Does GroupWise only execute the rule once per unique incoming email address?