That's because
[email protected] didnt send it :-)
These are spam messages from outside.
SMTP headers can be spoofed to make it look-like
[email protected] - is sending these messages.
I will send you a link on how to fix that.
What anti-spam solution are you using ?
if you are not using anything right now, please consider VamSoft ORF. it will prevent these kinda situations from happening again.
http://www.vamsoft.com/There is a 30 day trial. and it costs $239 per server (much cheaper than paying it per mailbox).
thanks