When an item is created by email - how will mandatory fields be set? It looks like the process is setting the very first value from such a field? Could you confirm this behavior?
thanks for your question.
Mandatory (required) fields are not handled differently, they they will be empty after creation if they are not provided. The only exception is the status field - as that one can never be empty (it may lead to strange and inconsistent behavior), it is always filled up with the first incomplete status option.
You find more info about the email to app functionality in our help center:
I hope that helps - let me know if you have any further questions.