The local technician at one of my locations is getting a lot of messages the the queues are getting full. When I check them they do not seem to be so full, but I do find occassional invalid domains, and of course, they are recieving firstname.lastname@example.org NDR messages.
Exchange is secure, I'm not relaying, so now through research I've come to the conclusion that Recipient Filtering is the next step. I am able to turn it on, and can view the difference both in message that is returned to the sender and in the fact that a queue is created when Recipient Filtering is off, but not created when Recipient Filtering is on.
I have also read that this can leave your mail server open to Directory harvest attacks since the SMTP communication is quite a bit quicker than the normal process of generating a NDR after the fact. I have found that there is a SMTP Tar Pitting feature that is available on Exchange 2003 on Server 2003. The way to set it up requires that I add a key to the Registry, which I'm comfortable doing. The only issue i have is that I'm adding a Key, and not looking for one that is there to indicate that Tar Pitting is valid on my Small Business Server 2003.
So, Is Tar Pitting available on Small Business Server 2003?