I migrated my account ages ago, and I keep getting emails telling me to migrate anyway. These messages are sent to the Microsoft address I migrated to.
I contacted support, and they told me everything’s fine, my account is properly migrated, and that I should ignore these messages, since they’re probably attempts at phishing. (That look 100% legit, might I add. Nothing about these messages looks alarming or wrong in any way, which is what made me contact support in the first place.)
That microsoft account of mine never received any questionable messages before, so thanks for leaking my data to malicious actors, I guess.