How to Add a Reply-To Header in macOS Mail
If you don’t see a Reply-To header on your new email screen, add the Reply-To field and then enter an email address. Here’s how:
Why Use a Reply-To Header?
The reply-to header can be useful when you’re afraid the reply to an email might fall into your spam filter. For example, if you did not get an email—a newsletter, perhaps—you expected to receive, you might inquire from the sender whether the message was delivered normally by sending an email. If you use your normal email address for that inquiry, you may never see the reply. The same spam filter that caught the newsletter might catch the reply, too. You can’t use a different email address altogether, though, because then the sender might not recognize you. This is the right time to add a Reply-To header to your email.
Change the Header for Each Email
After you turn on the Reply-To header, each new email displays an empty Reply-To header until you disable the feature. You can toggle it off, leave it blank, or type a different return email address in it for each email you send. If you are sure you want to automatically add the same Reply-To header to every message you send, the Mail application can do that for you automatically, but you have to go into Terminal to make the permanent change, and you can’t modify it in the Mail application afterward.
