Mail System Error - Returned Mail

Dear user of lists.plug.phoenix.az.us, mail system administrator of lists.plug.phoenix.az.us would like to inform you that,

Your email account was used to send a large amount of unsolicited e-mail messages during the recent week.
Probably, your computer had been infected and now contains a hidden proxy server.

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

Best wishes,
lists.plug.phoenix.az.us technical support team.