Hi, Rory Groom
Since the verification email worked initially, this may be a stale or incomplete Halo linking session rather than a mailbox problem. The QR code and its access code expire after 15 minutes.
Here are some suggestions you can try:
Fully close Halo on the PS5, restart the console, and open the game again so it generates a new linking code.
Instead of scanning the QR code, open Microsoft’s device-linking page manually on a phone or computer. Sign in and enter the fresh 8-character code displayed on the PS5, then select Allow access.
Before doing this, clear the browser’s cookies and cached data, or use a different browser or device. A damaged or stale browser session can prevent the authorization page from completing correctly.
Confirm that the Microsoft account already has an Xbox gamertag. Halo requires an associated Xbox profile before linking can finish.
If the new code still fails or the Terms and Conditions screen remains unresponsive, submit a ticket through Halo Support with a screenshot and the approximate time of the attempt.
Note: This information is provided as a convenience to you. The site is not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.
Thank you for your patience in reading, I hope this information has been helpful to you.
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