[Fwd: [PEAR] Delivery reports about your e-mail]

Hello pear lists webmaster, I received a notification telling me there were reports my e-mail was used to send huge amounts of unsollicited email. I hereby forward the message. I don't know what to make of this. I am pretty sure my Mac is not infected or running a trojan. This Mac is not running a mail server. Does this mean the server of my ISP is compromised? I find that rather hard to believe but if there are signs that this is the case I will definitely take action. At this point I have no detailed information I could forward to my ISP to investigate. At this point all I can do is ignore the warning until I have more details. Thank you, Steven