I don't have a Blizzard account, but have had a few emails now like this:
It has come to our attention that you are trying to sell your personal Diablo III account(s).
As you may not be aware of, this conflicts with the EULA and Terms of Agreement.
If this proves to be true, your account can and will be disabled.
It will be ongoing for further investigation by Blizzard Entertainment's employees.
If you wish to not get your account suspended you should immediately verify your account ownership.
You can confirm that you are the original owner of the account to this secure website with:
htt ps:/ /us. bat tle.n et/lo gin/en/?ref=http%3A%2F%2Fus.battle.n et%2Fd3%2Fen%2Findex&app=co m-d3
Login to your account, In accordance following template to verify your account.
* First and Surname
* Secret Question and Answer
Show * Please enter the correct information
If you ignore this mail your account can and will be closed permanently.
Once we verify your account, we will reply to your e-mail informing you that we have dropped the investigation.
Account Administration Team
http:/ /ww w.blizzard.com/support/
Diablo III , Blizzard Entertainment 2012
Very phishy - but it would perhaps scare some people who did have accounts there into giving their secret data away! As you might expect, hovering over the "link" provided shows a different address, too long to be shown in full...to be on the safe side I've added a few spaces here to disable it. Read it carefully and it's pretty unconvincing - and why would logging in to their site disprove allegations about account selling?
The moral is, however convincing and official an email seems, do not use links it provides to try to log in to your game account.