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

Use a Reply-To header to outsmart your spam filter

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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.

Why Use a Reply-To Header?

Oh, that spam filter! You did not get an email — a newsletter, perhaps — you expected to receive. You 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 cannot 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.

What's the Smart Email User to Do?

Set the Reply-To header of the message to an alternate email address. The message goes out using your regular email address, but as soon as the recipient clicks Reply, the alternate address comes into play. All replies go to that address instead of to your regular address as it appears in the From header.

In Mac OS X Mail and macOS Mail, you can set the Reply-To header easily for each message you send.

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. Open a new email screen in the Mail application on your Mac running the Mac OS X or macOS operating system.
  2. Select View > Reply-To Address Field in the Mail menu bar to add a Reply-To header to your email, or use the keyboard shortcut Command+Option+R to toggle the Reply-To field on and off in an email. 
  3. Type the email address to which you want replies to go in the Reply-To field.
  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.