Sending previously sent emails to new valid email addresses

[djmy]

I have a client who is getting calls from people saying that he is sending them many (one case over 70) copies of emails that he has previously sent to a different user.

He's running Outlook 2000 on Windows XP Pro. His McAfee Anti-Virus Definitions are up-to-date.

The only Anti-Virus warning he's recieved tells him that there is suspicous email activity - multiple emails contain the same subject line.

What virus / malware is this?

Thanks

 

[Xemus]

Many of the latest viruses exhibit mass-mailing functions, but most have their own SMTP engine, so they don't go directly through the mail client (Outlook Express, Outlook, etc.)
Has the client tried a second scan (like a free online scan) to verify that Mcafee is doing it's job correctly?
Links here:

http://www.closedsocket.com/links.html

http://www.closedsocket.com