The problem here is that the --send-mail-level and friends actually take an enumeration. But the validation code and GUI expects an enumeration to be “on of them”, but this particular enum is actually a flag, so multiple can be entered.
I think a short term fix would be to change the option type to String such that the user can enter the values, and it matches the help text. This will not break anything for existing users, as it just means they can do more.
It was supposed to work like this I think. But looking at the code, it no longer works that way.
It is certainly easier for the user.
I am not sure we gain anything from allowing multiple options, so maybe we should just change it?