Managing personal Outlook.com account settings, security, and privacy
Hello Evangelos Nichlos,
The old password in the extortion email is concerning, but by itself it doesn't necessarily mean your Hotmail account was recently accessed. An old password can come from an earlier credential leak.
I would first check your Microsoft account's Recent activity and look specifically for a successful sign-in you don't recognize.
- If you find one, select This wasn't me or Secure your account, then change your password and review your security information.
- If you don't find any unknown successful sign-ins, that would make the old password alone much less useful as evidence that the Microsoft account itself was accessed.
Since messages are also returning after you delete them, I would check your Outlook Rules and Forwarding settings and remove anything you don't recognize.
For Microsoft to review the account further, you can also use the Microsoft account Sign-in Helper.