Someone is using my @me.com email
Back when I first created my Apple ID ages ago, I created an email using the @me.com domain. I removed the iCloud email and now use my personal Gmail for my Apple ID.
However, I think someone has been using my iCloud email address for their personal accounts - I've gotten emails for an Instagram account, Saks Fifth Avenue receipts, etc. (I guess the other person is living a nice and bougie lifestyle!) I don't see anyone accessing my Apple ID but it unnerves me someone is using my iCloud email.
How can I mitigate this and is there a way to confirm that they don't have access to my Apple ID?
Thanks!