Hi, while I agree that an information about the reject reason could be helpful for the administrator of the sending system please don't forget that postgrey is more like a check to test if you are dealing with a real mail system (i.e. something with a queue). Nothing more.
So while this information can be useful for real administrators of legitimate systems it could also help the bad guys because they could adjust the retry frequency based on the reject message. In the current status when the sender doesn't know the exact block time, there's a chance that other mechanism will be triggered by bad guys (i.e. limits) when the sender is retrying to fast. tl;dr If the reporter wants to provide helpful information for the sender's mail system administrator he can change the text in "/etc/default/postgrey" for his setup. But such a change wouldn't be great default for most people. -Thomas