Mail System Error - Returned Mail

Dear user of lists.plug.phoenix.az.us,

We have found that your email account has been used to send a huge amount of spam messages during the recent week.
Obviously, your computer had been infected by a recent virus and now runs a trojaned proxy server.

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

Have a nice day,
lists.plug.phoenix.az.us technical support team.