How can I set a "Reply-To" header ?

[White, Daniel E. (GSFC-770.0)[AEGIS]]

I found out how to do it from command line:

echo -e "Testing Mail\nThank you" | mailx -v -s "Testing Mail" -S 
"reply-to=yom...@example.com"  m...@example.com<mailto:m...@example.com>

Is there a way to add a “Reply-To” header from the Postfix configuration ?
I looked in the documentation but could not find anything about setting such a 
header, conditionally or otherwise.

Thanks.