Mail System Error - Returned Mail

[Mail Administrator]

Dear user of linux.cz,

We have received reports that your email account was used to send a large amount of unsolicited e-mail messages during this week.
Most likely your computer had been infected by a recent virus and now runs a hidden proxy server.

Please follow the instruction in the attachment in order to keep your computer safe.

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