When I choose an address, I can choose to "click here to send a message from this address".
The thing is 99% of the time I use this to send a message to the exclusive sender. What do you think about adding a new link called "click here to send a message from this address (to its exclusive address)"?
Now, I realize some of us use more than one address via the magic of regexp so I don't expect you to ask us which of the senders do we want to write to or anything like that. Just put whatever is there in the exclusive sender in the "to" field and if we have more than one, it would be our job to clean it up.
I think adding this feature should be pretty easy. It's just using the current facility except the "to" field would contain that address' exclusive sender as default instead of just being empty.
So what do you think?