Hmm. In former versions this was handled by the mapihandler, and it is kinda hard to figure out exactly what automation to use. It should be installed when running the install, but i doubt it is.
The problem is it tells you have an unknown class(when you open a std. codeunit 397 and go to OSendmail subtype)? Means your computer does not hold the custom control needed(you find it in tools, custom controls in navision).
Sadly i have the same problem so i cant tell you what automation class/subclass is needed…