If it went to your contacts, see if you can get them to give you the email header as well. If the ip matches, you may have a larger problem on your hands than an SMTP server. Most likely something got a list of your contacts & spammed them.
The only 2 I can get at this time are both msn and the headers have been stripped off. Assuming that they do, what should I do? Can I do something? Do I need to do something?
Edit: Do I have a virus on my computer?
See if you can contact Yahoo. They'll have access to the server logs. They may not offer much assistance though.
Either there is virus in your system or someone hacked your mail id. Try to check out what happen. Change password and other information of your account.
Thank you but I've already done that.
Did you ever discover the problem?
I didn't look into it anymore.
Interesting article. Please write little more next time on the same theme.
Your bloody account has been compromised change your password and the backup question as well as any mail addys you have linked to that account eg the one where they sent your lost password to.