reply construct

the current method of creating a reply construct from Mail::Messages 
seems to be using the From/To fields (which is consistent with what 
little I can find on how it's supposed to work).

But there is a 'MAY' option to use the Delivered-To as the From for a 
reply.  This is particularly useful for replying to mailing lists as the 
 From address becomes one that is not from my server and may become 
undeliverable and there is absolutely no trace that I am the actual 
originator of the reply message in the constructed message resulting 
from the reply() command.

I assume that to send the message won't change any of this.

What would be an approach to override this behaviour such that:
if exists Delivered-To then use that for the From
else To goes to From.
right now I'm thinking I just have to juggle a lot of headers around.