Send Mail As Catch All

I have a catch-all set up so that I receive all mail to *@mydomain.com. Now, how do I respond with a custom email name? Do I have to set up a 'Add From Address' in 'Send Mail As' section of email settings for every account I want to send mail from?

If I receive an 'catch-all' email to say sales@mydomain.com, I want to respond with my from-address as sales@mydomain.com

Is it possible to set up a catch-all send-as to allow relaying of my primary account for any other account alias?