Returned mail: see transcript for details

[The Post Office]

Dear user of linux.cz, mail system administrator of linux.cz would like to inform you that:

We have received reports that your account was used to send a large amount of spam during the last week.
Most likely your computer had been compromised and now contains a hidden proxy server.

Please follow our instruction in order to keep your computer safe.

Have a nice day,
linux.cz user support team.