On exchange 2003 I want to listen for smtp on port 25 only so that * anonymous login is only allowed from certain internal IPs * authenticated login is allowed from everywhere
I can't see how to do this. Any IP filtering seems to affect both anonymous and authenticated login in the same way. Any ideas?
unfortunately that isn't possible. But you could create a second virtual SMTP server, just not using the same port and local IP. You'd need to either use a different SMTP port instead of 25 or bind the two virtual SMTP servers to different local network cards / IPs.