You are definitely being too optimistic :-( In order to implement the new
format, you need an intelligible delivery error to begin with. If your
software says "An error occurred delivering your mail to one or more of
its recipients" and leaves it at that, your existing code probably
doesn't have access to the data that would be needed to implement the new
format. I also doubt that this will catch up quickly. Sendmail will use
it, and then a few products here and there, maybe. Implementing the new
format doesn't provide much of a benefit to the site running the
software, it just helps remote list owners. I expect it would be one of
the last items in the wish lists.
Eric