Allow Domino to capture client side configuration information

You're trying to determine which servers or appliances are connecting to the Domino SMTP relay servers using IP addresses versus hostnames. You want a way to distinguish, within the console logs, which devices are using hard-coded IP connections. The goal is to ensure these connections are transitioned to hostnames instead.

Unfortunately, Domino will not have the client side configuration information. Any client configured to use host name will do DNS lookup first. Resolve the domain name/host name to IP address. Then connect to the IP address. Also, when an SMTP client connects to Domino SMTP, the TCP connection itself always originates from an IP address. Domino receives the source IP and then attempts a reverse DNS lookup (PTR record) to resolve that IP to a hostname.