Server “003 Exchange

Hi there everyone

I have a server 2003 running exchange, i noticed over the last few days in the report viewer that the administrator had been sending out 1000’s of mails once i looked in queues i noticed that there was a lot of mails being sent out by the postmaster, I have scanned the server for viruses but nothing has been dicovered, i have also run some well know viruses tools such as mydoom and so forth.

I have looked for this problem elsewhere but cant seem to find an answer.
Is there anyone out there that has this problem or had it and knows how to resolve this issue

Many thanks
Garry