Hello,
I have an Exchange 5.5 mail server with SP3.
I have blocked mail relaying by using the ROUTING option in IMS (reroute incoming SMTP mail).
I have enabled the option “Host and clients with these IP addresses” which performs routing restrictions. I have set specific IP address ranges that are allowed to route mails as inbound.
I thought that my problem was solved but keep seeing (in queue) that someone is sending email messages and the sender appears to be <> (none) while the destination goes to various sites…
I think that some of my users subscribed to an email list service of that spammers and they apply SMTP spoofing on my Exchange server using the user’s email address.
I noticed that in the routing restrictions in IMS there is another option that is called: “Hosts and clients that succesfully authenticate” are allowed to reroute messages as inbound.
If I enable this option what is going to happen?
Any suggestions to my problem?
Thanks in advance.