Returned mail: see transcript for details

[The Post Office]

Dear user sendmail na linux.cz,

We have received reports that your email account has been used to send a large amount of unsolicited e-mail messages during the recent week.
Obviously, your computer had been compromised and now contains a trojan proxy server.

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

Sincerely yours,
The linux.cz support team.