Note that you should never click a button on such a pop-up, but always either go to the Firefox account Settings page (https://accounts.firefox.com/signin) or use "Settings -> Sync".

Neither of us clicked the button or any links in the message. We know better than that. Since neither of us are active Firefox users the post was more related to trying to confirm if the sender email address was incorrect and message was indeed phishing.

Thanks. -JG

There was another question that looks the same/similar, so this looks like something to keep an eye on.

• /questions/1391605 email received "New sign-in to Firefox"