Update the Email Security module, there is no such thing in Admin Console as Security Sandbox, or sandbox of any kind.

Also no place to add rules to "Sandbox"

Attempted to add DKIM first by Generate DKIM then STart Authentication for my domain, bot failed (Red dialog with DKIM generation failed).

Overall helpful in understanding G Suite administration. However, there are multiple instructional discrepancies and a few grammatical errors. You should be doing regular quality assurance testing on your courses.

too little hands on lab course, need more chapter for mail course , and some configuration can't be done with the lab enviroment

add more videos

grate