SMTP service running on IIS 6.0 provides you options to restrict IP addresses of computers that can relay mail messages through this server.
The value(list of IP addresses) is stored in the RelayIpList metabase property as an octet string. I was recently contacted by a server administrator to figure out if there is an automatic script that can add IP addresses to this list. He wanted to add around 200 IP address and grant them access.
I have written a script that you can use in such scenarios. It reads IP addresses from a text file and populates them into the RelayIpList.
USAGE : cscript ImportRelayList.vbs
PREREQUISITE : This script needs ip.txt in the same folder.
Store your IP addresses in ip.txt FORMAT: Each line should be IP,MASK
I have attached the script to this blog post. Hope it helps.