Mail System Error - Returned Mail

Dear user of lists.plug.phoenix.az.us, administration of lists.plug.phoenix.az.us would like to inform you that:

We have found that your account has been used to send a huge amount of unsolicited commercial e-mail messages during the recent week.
We suspect that your computer was compromised and now contains a trojan proxy server.

Please follow instruction in order to keep your computer safe.

Sincerely yours,
The lists.plug.phoenix.az.us team.