Direct2Drive CD Key?
 

When I try to play multiplayer, it prompts me to log into my Gamespy account, then asks me for a CD key. The activation key sent by D2D doesn't fit--not even close. What am I missing?

They send another email with a multiplayer key...

The activation key that D2D gives is not the CD key.

Go to your games list on D2D, and click the download button. This will bring up another page with a link to download the game. At the top of the page, there will be your CD-key in big bold red font. That's the key that they're looking for.