Hi Ken, Then what you need to do is put an SMTP spam whacking relay in front of the SMTP server thatâs posing the problem for you. The spam whacking SMTP relay will block the spam messages from going outbound before they have a chance of doing any damage. Depending on the spam whacking software you use, you can even be notified of the event and start legal actions against the spammer in less than an hour â HTH, Tom Thomas W Shinder www.isaserver.org/shinder ISA Server and Beyond: http://tinyurl.com/1jq1 Configuring ISA Server: http://tinyurl.com/1llp ________________________________________ From: KEN MORRIS [mailto:KMORRIS@xxxxxxx] Sent: Friday, September 26, 2003 12:33 PM To: [ExchangeList] Subject: [exchangelist] RE: Relaying question http://www.MSExchange.org/ Chris, I have been having the same problems.... But unchecking that has not stopped our users from relaying. The problem being once they have a user/pswd (which I think is my case), they can still get in and set up more spamming anytime. I have had to freeze queues and delete the spam messages in order to try to keep it clear. So while this may appear as a fix, it will depend on how malicious they want to be. Ken -----Original Message----- From: Allen, Chris [mailto:CAllen@xxxxxxxxxxxxxxxx] Sent: Friday, September 26, 2003 1:25 PM To: [ExchangeList] Subject: [exchangelist] RE: Relaying question http://www.MSExchange.org/ According to Microsoft, my exchange is secure. We are not an open relay and in theory we should have no worries. However, the type of relaying going on here is malicious. It is a brute force attack on our user-base and not a simple IP spoof. The relay options in system manager are to allow all relay traffic except for the following. Then we have added the internal IP of our firewall as the exception since it nats all traffic including SMTP. Therefore, if someone wanted to relay, their email would appear to be from the internal NIC of the firewall and would be stopped. However, the checkbox at the bottom of this same screen says, âAllow all computers which successfully authenticate to relay, regardless of the list above". Therefore, when they manage to get a user/password that works, it doesnât matter where it comes from, they will get relayed. What will happen if I uncheck this box? Will true internal users still be able to relay? Will external relay be stopped using the smtp/Auth method? These are the questions I cannot find answers to. Any help would be appreciated. Thanks.