Dispute it.

Bans have been overturned before. If you haven't done anything wrong, you shouldn't be punished.

E: Just explain what you've been doing. Some processes related to account action are automated.
Ev2: Don't worry, 'final' decisions have been reversed. Oh, and as far as "boring" us with the rest of the email, it can provide some clarification

After a quick Google, I found the 'rest' of the email. (First link was a wow-europe link)

Online trading refers to the exchange of in-game content for real world money, and includes, but is not limited to, the sale or purchase of gold, the sale or purchase of experience in the form of powerlevelling, and the sale or purchase of honor points, reputation or items.

Account access is the responsibility of the account owner and account sharing is against our Terms of Use (http://www.wow-europe.com/en/legal/termsofuse.html). Therefore, should you believe someone other than yourself (the account owner) has committed this violation of the Terms of Use with your account, these sanctions would still apply, as our action is taken against the account, not the individual.
Ev3: Might be a good idea to make sure your computer hasn't been compromised. (To be on the safe side)