Hi all, I am a little puzzled here. I am hoping someone out there maybe experiencing similar issues with unrecognised mail bouncing back. Basically, I have a user here that keeps getting mail delivery notification from people she doesn't know about how they'd received a message from this user and the message was blocked due to virus infection or virus infected attachment. This user is using an XP box. She uses just one machine. She claims she doesn't have a system at home. I have checked the user's PC, disabled system restore and run Symantec antivirus scan with latest definition files, run Netsky removal utility, checked running processes for any dodgy unidentified process and I have found nothing. Nothing whatsoever. Yet the user just received a message back from some external person saying they'd received a message from this user which was infected with a virus. Any ideas. We are using 2 different Antivirus products here plus Spam filtering gateway and exchange specific antivirus. Any thoughts much appreciated. I am now thinking about monitoring traffic on that machine over a couple days to see if anything shows up there. Thanks very much in advance.