Command By Mail question on Custom Fields

To List,

I’m not sure if I missed something in my install or not and I hope someone
here can help. I am using CommandByMail and it’s working pretty good.
However, if I put in an invalid value for a CF defined as “Select One
Value” in my email, the ticket gets updated with that erroneous value,
rather than default to “No Value”. At least it looks like that when I click
the “Display” button. If I actually go into the “Update Ticket” screen, the
bad value isn’t there.

Is there some code I forgot to install that edits for invalid values before
updating the Custom Field in the TIcket?

Is there some code available the will edit any value sent against the select
list for that CF?