Outlook Express sent message

[Jean Noel Camoin]

I just send an email message to a specific collegue
working next to me within the same office. To my surprise,
other collegues received the same message.

I ran Norton Antivirus, thinking it could have been a
virus. No virus was found.

Could you help me in directing the way to troubleshoot
this problem?

Many thanks.
Jean Noel