Have you seen any pop-up in BB?
Late is better than never.
And in any case, you can do it the same as with the auctions.
When the price is not right (or the message is not, in this case), there is a message at the top of the screen (after sending the request) telling you your fault.
Your message will not be deleted and will allow you to deal with your error.
Summary - Think on what can be done, and on the concept itself and not only on what is bad.
Stop being pasimistic, it is the new year's eve (or new civilian/gregorian year, as we call it here).