Port 465 for TLS / SSL has been deprecated, but the default value on the server doc is 465. This default value should be changed to 25. This is found on the server doc, Ports - Internet Ports - Mail, SMTP Outbound, SSL Port Number.
Also, the default value for TCP/IP port status should be Negotiated SSL rather than Enabled and the default value for SSL Port should be set to Disabled so TLS will be used by default.
Here is a related idea too: https://domino.ideas.aha.io/ideas/DOMINO-I-518