Now, this of course fails with “hide my email”. What’s the appropriate/standard way to handle this? Should I be using urls with invite codes instead of associating the email itself with access? I’m a little hesitant to do that since the code would have to persist in session and the business logic would have to occur on the login portal, since the mobile/desktop apps don’t share web cookies. Is deep linking the answer?

Frustratingly vague. I was unable to reproduce when the original article was posted. I did not test exhaustively, but I was able to get HME to reject messages in various ways (mostly by sending oversize messages) and none disclosed my real address because they were rejected before any rewriting to the final address occurred. And in looking at messages that were delivered, I didn't see any additional SMTP servers in the path that would reject the message.

The most I was able to leak was a DMARC header showing my real domain, but even that only occurred when I replied to an HME email from my real (non-icloud.com) domain. When I updated HME to use my icloud.com address, even that leak went away (but it did make it clear that HME was not sanitizing message headers).

Maybe if you have HME setup to forward to a non-icloud.com domain and that domain's SMTP servers rejected the message as spam, I can see how this could occur. But if forwarding to an icloud.com address, no way this should've been able to happen in the first place.

I wish they'd included a sample message including full headers to see the vulnerability in action. Where in the delivery path was the bounce being generated?

I want more details.

> Now Apple says it has been fixed, we can add that, in simple terms, it required sending a target Hide My Email user a message that got rejected as spam.

I would note that Mac Mail app (I haven't tested iOS Mail) still has an Apple Account email address disclosure vulnerability, though this requires the user to reply to a maliciously crafted email. The vulnerability affects all users of Mail app, even if they don't use Hide My Email! https://lapcatsoftware.com/articles/2026/7/9.html

Like always. Apple fixes vulnerabilities _if_ and _after_ they are publicly published.