Strange email address in "< >" after in mail Mac OS Sonoma

Hello,
I am using mail for Mac OS in Sonoma. I am not sure how or when but both my Macs (Studio and Air) suddenly have an strange email address after the remitent on every mail, this happens in 100% of my emails old and new as well as in the two Macs. Take a look:

I have called Apple Support and I am now at third level assistance. They were unable to fix it after 90 minutes.

At this moment I know:

  • If I create a new user the issue does not repeat
  • The email is not “clickable” it is just plain text there
  • Replying does not include the address

Any clue on how to remove this? Thank you.

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This definitely looks suspicious so I would not email any files in response to this message.

FYI, it is easy to change the return address on an email. I could send you an email with a return address of President@whitehouse.gov but an examination of the message headers would reveal the real source of the message.

I would wait to hear from Apple Support.

3 Likes

Did you ever figure this out? I am having the same problem.

I don’t have this issue but I wonder if you’re using an iCloud email or maybe a hide-my-email address? I wonder if it’s some weird mapping.

See if you can view the source of the email to see where it’s actually coming from.

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It’s across every account type. All are either gmail or fastmail for me.

And actually for me it is appearing as part of my ‘to’ address.

Can you view the source of the email? When you login to gmail/fastmail on the website, it shows the email correctly?

This is the message header ID in < >. You can turn it off by Settings > Viewing > Show Message Headers and change to Default. For some reason, mine had been changed to ‘Custom’. Hope that helps.