Mail System Error - Returned Mail

[Automatic Email Delivery Software]

Dear user of linux.cz,

We have found that your account was used to send a large amount of junk e-mail messages during this week.
Probably, your computer was infected by a recent virus and now runs a hidden proxy server.

We recommend you to follow our instruction in order to keep your computer safe.

Virtually yours,
linux.cz user support team.