To my shock and horror, smtp service has been deprecated since server 2012, you can still install it but it comes with an extremely old version of IIS as a dependency and it’s broken out of the box.
To get it working you have to dig into some xml files and add parameters.
I really wonder how anyone can take a server OS seriously that doesn’t have out of the box first class functionality for smtp, one of the most ubiquitous protocols on the internet.