I just got an email saying this.

#1 - Aug. 18, 2013, 10:31 a.m.
Blizzard Post

Greetings!

It has come to our attention that you are trying to sell your personal Guild Wars 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 ArenaNet 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:

(I omitted the link here)

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.

Regards,

Account Administration Team
Thanks! —The ArenaNet Team

Is this a scam? I have not tried to sell anything.

#24 - Aug. 19, 2013, 9:34 a.m.
Blizzard Post

Guys, instead of posting a million comments, could you kindly simply link to one or both of our official threads on this topic? The mail thread says it all, provides helpful samples against which any player can compare his/her incoming email, and helps keep the conversation about this focused:

A Note about Phishing thread

If the email is brand new — which this definitely is not! — you can also point to the merged, continuing thread here. Email from ArenaNet? Please Read