How to configure Mail v8.2 to supply a different default reply-to address in emails being sent? I'm using Mail v8.2 on Macintosh OS X Yosemite and would like to transition to a new email address.  Therefore, I'd like to keep using my old email address for the time being and I have configured my new address to forward all email to my old address.

Now, I just need to set up my reply-to in every email I send, to default to specifying my new email address, so that recipients will eventually start using my new email address over time and eventually I can pull the trigger and drop the old one and switch to the new one.

How can I configure Mail v8.2 to use a different default reply-to email address for each email I send?  I don't see anything in the Preferences, nor in the account settings.  I have a pacbell.net account for my old email address that is hosted by Yahoo.com.
In Mail, under the View menu, you can choose which fields to show or hide, including Reply To.