If it works from CWIS but not the printer then, the issue is screeshot 2. The details in the upper portion apply to what happens at the printer, and the bottom portion applies to the CWIS test page. Set the top one to something other than what it is currently on, then set it to None and reboot just to be sure.
In this day and age, no authentication is extremely rare, typically it means you are using a relay, and if that is the case you usually need to set it server side to accept any email from a specific IP (the printers) to be able to send without authentication.
That would explain the "same email works on another machine using the same settings" while failing here.
Office 365 and gmail both work that way.