My apple ID is being used on an iPhone. What do I do?

Change your AppleID's password here: https://appleid.apple.com

I am not sure if the e-mail is a phishing attempt.

Can you put a screen shot of the e-mail here?

Read here:

Identifying fraudulent "phishing" email - Apple Support

If you think your Apple ID has been compromised - Apple Support

TimK wrote:

When I turned on my computer this morning, I got the message:

"Your Apple ID is now being used for iMessage and FaceTime on a new iPhone. If you recently signed into "your iPhone" you can ignore this notification"

I don't have a working iPhone. The only iPhone I have has no SIM and is in a drawer.

So I cannot ignore this notification. But what the **** am I supposed to do? Who do I contact?

Contact apple support directly -- it can be a tangle with it allowing the account setup without really checking other accounts.

TimK wrote:

It wasn't an email. It was a notification on the screen, with the 'Messages' logo.

(I appreciate your help, by the way)

I don't think Apple send iMessage for such incident.

I thinks if you have given private info by clicking a link on a message, you should change the password again

using the official link here : https://appleid.apple.com

You can open a new browser tab and key in yourself to be sure.

TimK wrote:

It wasn't an iMessage. It was a notification window in the middle of the screen.

Linked to where: Messages or an e-mail?

It's a scam. Change your password just in case.