Thus far I have already got 4 of these mails.
I while back I tested how these 'hackers' get into your account. Basically what you do when you visit that website is you give them you game email and your game password.
I tried fake combos of emails and passwords and their website still says something like "Thank you, we have found you!" I can't remember exactly.
The rate at which these 'hackers' took to get into my account was a little under 10 minutes. I was prepared for this scenario and logged them out within 20 seconds and changed my password within 2 minutes.

Simple Advice: NEVER SHARE ACCOUNT INFORMATION!