, further logins do not require repeated two-factor authentication (2FA) for that specific machine. : The requests and responses in this flow generally use the Property List (plist) Implementation Context for Developers If you are developing a custom Mobile Device Management (MDM) solution
Some spam filters use this header as a positive signal —genuine Apple Mail clients rarely send spam directly. But beware: spammers can forge it. Never trust the header alone. x-apple-i-md-m
If you have ever dug into the raw source code of an email—perhaps to troubleshoot a delivery issue or inspect a spam header—you might have stumbled upon a strange, cryptic string: . , further logins do not require repeated two-factor
Apple Mail adds this header before handing the message off to your outgoing mail server. It’s not configurable in Settings, and it doesn’t affect deliverability. Never trust the header alone
Blackwood 4NT -- Grand Slam Authentication for Windows NT (10)
To strip these headers in Postfix, for example, add to /etc/postfix/header_checks :