I keep getting “News” from newsdigest@insideapple.apple.com I have not asked for. It is being sent to an email address which does not even exist (they can do that if you have a personal domain = something@mydomain.com).
I have refrained from clicking any “unsubscribe” or whatever else link. Everything goes straight to my spam folder. If this is spam then there must be somebody very busy doing editorial work, it looks quite tempting.
That is the correct return address for news summaries from Apple News when you request them(or allow them by default?)
The summaries should go to whatever address you used to sign into the News app, normally your Apple ID.
Several comments:
The addresses that appear in the message headers (e.g. the To: and Cc: headers) have absolutely nothing to do with message delivery. The actual address used to deliver the message is out-of-band and isn’t part of the message body. (This is why Bcc can work).
During the delivery process, each mail server that processes the message prepends a Received: header. If you view the full set of message headers, you can often (but not always) determine the actual source of the message and the address to which it was really sent.
That having been said, newsdigest@insideapple.apple.com is the address of a legitimate Apple mailing list. Assuming the return address wasn’t forged by a third-party. (The From: headers in a mail message, like all of the message headers, can be forged and are not reliable indicators of a message’s origin).
Assuming the mail isn’t forged, it is probably being sent to some address you have (or once had) on file with Apple. Possibly associated with your Apple ID, or a beta program subscription, or provided at a store for a purchase. Or a typo thereof (since you have your own domain, you probably get all mail sent to the domain, even if the mailbox name is wrong).
I would (after confirming the message’s origin, via the headers) send an unsubscribe request.
See also:
In addition to unsubscribing from specific Apple newsletters, you can shut down Apple spam.
Go to appleid.apple.com and enter your credentials. Then navigate to Privacy (bottom of the LHS panel) > Messages from Apple.