Source: HalfLife-2.nl

HalfLife-2.nl reports that a fake Steam e-mail is roaming around. The e-mail reports that there are some problems and that you will need to send your Steam account information to a certain e-mail. DO NOT do this. Valve will never ask for your information in this way. Here the fake e-mail:

From: "Steam" < accounts@steampowered.com >
Reply-To: "Steam" < steam-validation@mail.com >
To: "---@hotmail.com" < ---@hotmail.com >
Subject: Please validate your Steam Account
Date: Mon, 22 Nov 2004 21:39:45 +1100

Dear Steam User,

In order to continue using Steam you must validate your account by forwarding this message to Steam-validation@mail.com.
You must include your account information in this format in the message:
Username: (your Steam username)
E-Mail: (the email you registered your account to.)
Password: (the password you used to log in to your Steam account.)

Our database will be formatted soon, due to some damage caused by some users. We will need to record our active users and add them to our database once again.

You must validate your account within 30 days or eles your account will get closed. Thank you for your co-operation, Best regards, Steam account Managing Team.

As said this is fake, so if you have received such an e-mail, do not reply, just delete it directly.