How to Add and Change the Reply-To Header in Mac OS X Mail

Use a Reply-To header to outsmart your spam filter

Illustrated human figure launching email via sling shot
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By default, responses to emails you send from the Mail application in Mac OS X or macOS are sent to the address in the From field of your outgoing email. If you have several email accounts, you use the arrow at the end of the field to change that address.

If you prefer to have email responses sent to a different address than the one in the From field, add a Reply-To header to the email for this purpose and enter a different address.

These instructions apply to Mail 11 and higher.

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.

Using a Reply-To Header in an Email in Mac 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:

  1. Create a new message by clicking the Compose button in Mail.

    Apple Mail with the New Message button highlighted
  2. Select View > Reply-To Address Field in the Mail menu bar to add a Reply-To header to your email.

    The keyboard shortcut is Command-Option-R.

    Apple Mail with the Reply-To Address Field command under the View menu highlighted
  3. Type the email address to which you want replies to go in the Reply-To field.

    An email in Apple Mail with the Reply To field highlighted
  4. Continue writing your message and send it as normal.

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 or 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.