Just saw this on another forum, so passing it on
"Your Apple ID was used to sign in to iCloud via a web browser.
Date and Time: May 4, 2020, 1:12 PM PDT
Operating System: Linux
If the information above looks familiar, you can ignore this message.
If you have not signed in to iCloud recently and believe someone may have accessed your account, go to (Service Support) to verify your identity under 24 hours before disabled permanently
Apple Support"
There is a link in the mail that goes to a site in Indonesia which attempts to get you to sign in with your apple ID so that they can take over your account.
Don't follow the link. Don't sign in from the link. If you have had this mail and have followed the link immediately change your apple ID password.