Emails containing a virus very rarely if ever actually come from the email address "suggested" in the from section.
Most email virus scan the infected computer for email addresses and send themselves to and from those email addresses, this is to try and hide where the virus actually is.
Dustdees i would guess that the emails never originated from the servicewanted site, but that they originated from somones infected machine with both your email address and the servicewnated email address on.
Regards
Phil