This is a similar question to the one from ""Email headers with mail app (Big Sur 11.1, MacBook Pro 15' retina, mid 2014)": https://discussions.apple.com/thread/252326178 (which is now closed, without an answer).
MacBook Pro 15″, macOS 10.15
jaaredroach wrote:
If UserHeaders currently has this value '{"Reply-To" = "my.name@apple.com"; }' , then how do I change it to not have any "Reply-To" value at all?
See if this gets you any closer:
Quit Mail.
To remove all UserHeaders copy and paste:
defaults delete ~/Library/Containers/com.apple.mail/Data/Library/Preferences/com.apple.mail.plist UserHeaders
Relaunch Mail.app and test
jaaredroach wrote:
If UserHeaders currently has this value '{"Reply-To" = "my.name@apple.com"; }' , then how do I change it to not have any "Reply-To" value at all?
See if this gets you any closer:
Quit Mail.
To remove all UserHeaders copy and paste:
defaults delete ~/Library/Containers/com.apple.mail/Data/Library/Preferences/com.apple.mail.plist UserHeaders
Relaunch Mail.app and test
Use Systems Preferences to give Full Disk Access to Terminal. Then the command suggested by leroydouglas should work.
It is possible to send an email from one address, but to put in the header that replies should be sent to a different address. That is the purpose of a "Reply-To" header. Using "Reply-To" has many wonderful uses, but it also can be weaponized by spammers. This practice has come to be known as 'spoofing'. As a result, many spam-blocker software will treat _all_ email with a "Reply-To" header as spam. So if one uses a "Reply-To" header, there is a good chance that your intended recipient will never get that email, because they are downstream of an overly aggressive spam-blocker. And one is unlikely to realize that the recipient has not gotten the sent email. So it may be best practices in some instances to not use a "Reply-To" header, whatever its other advantages might be in that context. Therefore, if one has been using a "Reply-To" header in the past, it might be useful to stop using it. This is true in Macintosh / Apple Mail. And probably universally true.
This seems to work, in that I don't get an error with the command (like I do in the answer below). I can even "verify" that it does work by checking with:
defaults read com.apple.mail UserHeaders
and the defaults appear to have changed. However, when I restart Mail (even if I restart the computer). Mail continues with its previous behaviour as if nothing has changed. Somehow Mail is preserving this setting and resetting it, even though I changed the defaults file.
Safari's preferences are sandboxed. Have been for a few years. The file you are editing is from a previous version of Safari left over in your un-sandboxed system file hierarchy. So it has no effect on your Mail program.
jaaredroach wrote:
Using "Reply-To" has many wonderful uses, but it also can be weaponized by spammers. This practice has come to be known as 'spoofing'.
Use of the Reply-To header has nothing to do with e-mail spoofing. With true e-mail spoofing, spammers or scammers take advantage of malicious or poorly configured servers to send an e-mail with a fraudulent "From" address. Reply-to is not necessary at all.
As a result, many spam-blocker software will treat _all_ email with a "Reply-To" header as spam.
If they are doing that, then they are doing it wrong. It wouldn't surprise me. There is a log of fraudulent and scam software being used to. "Security" software is particularly notable for this kind of fake security that does more harm than good.
So if one uses a "Reply-To" header, there is a good chance that your intended recipient will never get that email, because they are downstream of an overly aggressive spam-blocker.
In spite of everything that I've said, I don't disagree with this. I have no data to confirm it, but it sounds plausible. There are lots of scam ware security apps installed in the world. I don't know what it is, but scam apps are extremely successful. It's like printing money.
I run a software business where I send out a fair amount of automated, but legitimate e-mails -namely purchase receipts and license codes - people should want those and keep them. A significant portion of this e-mail never arrives. It isn't even unusual for recipients to flag those receipts and license code e-mails as spam.
So yeah, e-mail is definitely not reliable.
So it may be best practices in some instances to not use a "Reply-To" header, whatever its other advantages might be in that context. Therefore, if one has been using a "Reply-To" header in the past, it might be useful to stop using it. This is true in Macintosh / Apple Mail. And probably universally true.
If you aren't actively using "Reply-to" then there is nothing you need to do. I don't really think that usage of "Reply-to" is going to be any more likely to cause a problem than any other headers. E-mail itself is simply not reliable. I regularly get a lot of junk mail and I regularly have to go into my Office 365 quarantine folder and pull out the legitimate e-mails that have been miscategorized as junk.
You should be able to do what you want to do with the following command:
defaults delete com.apple.mail UserHeaders
jaaredroach wrote:
This is a similar question to the one from ""Email headers with mail app (Big Sur 11.1, MacBook Pro 15' retina, mid 2014)": https://discussions.apple.com/thread/252326178 (which is now closed, without an answer).
What exactly is your question...
Read receipts are obsolete.
Mail User Guide for Mac - Apple Support
What's new in Mail on Mac? - Apple Support
jaaredroach wrote:
If UserHeaders currently has this value '{"Reply-To" = "my.name@apple.com"; }' , then how do I change it to not have any "Reply-To" value at all?
You are trying to hide your return email address? Is this the question...to what end?
Is this an old issue, new issue, what changed?
Are you using the Apple Mail.app or some other email client?
What is Hide My Email? - Apple Support
Using your @icloud.com email address - Apple Support
Use email aliases on iCloud.com - Apple Support
Doesn't seem to work. I get this:
>defaults delete ~/Library/Containers/com.apple.mail/Data/Library/Preferences/com.apple.mail.plist UserHeaders
2021-10-07 11:36:53.620 defaults[53648:1719337]
Domain (/Users/myusername/Library/Containers/com.apple.mail/Data/Library/Preferences/com.apple.mail.plist) not found.
Defaults have not been changed.
>
I tried giving myself edit permission using "get info" but I still don't seem to be able to edit the file. I think I need to combine the answer leroydouglas gave above (with the full path to the sandboxed defaults file) with your advice about permissions.
If UserHeaders currently has this value '{"Reply-To" = "my.name@apple.com"; }' , then how do I change it to not have any "Reply-To" value at all?
OK. Thanks. So that's why I cannot change the settings the way I have been trying. But how do I actually change them?
You have two choices. One is to move the file in question out of the sandbox, edit it, and then move it back. Two is to edit the file in the sandbox, in which case you need to give the program trying to edit the file permission to do so (in this case, Terminal).
How to change UserHeaders in Macintosh Mail?