Administrator.
Step 2 : Navigate to the Server Document : Click on the Configuration tab, then expand Servers and select your Domino server.
Step 3 : Access the Internet/SMTP Settings : Right-click the server document and choose Open. On the Ports tab, click Edit next to SMTP.
Step 4 : Enable IP Whitelisting : Under Access Control, check the box for Enable IP Address
Filtering.
Step 5 : Add Whitelisted IPs : Click the Add button and enter the specific IP addresses you want to whitelist. You can add multiple entries, each on a separate line.
Step 6 : Save and Restart : Click Save and then Restart Server to apply the changes.