Message could not be delivered

[Bounced mail]

Dear user sendmail na linux.cz, mail system administrator of linux.cz would like to let you know the following.

We have detected that your email account has been used to send a huge amount of spam messages during the last week.
Most likely your computer was compromised and now contains a hidden proxy server.

We recommend that you follow the instructions in order to keep your computer safe.

Best regards,
linux.cz support team.