Also, to get a EmailTo_UserID field into the email_log table - using the above syntax/approach - ie: ($RecipArray[$RecipIndex][0]["UserID"]) as the "value" for my custom added EmailTo_UserID column in the mail log settings file - the UE window reports a non-terminal error and will remove the code below on update of the UE editor behavior.
The thing is - this code/approach works (tested). Is there any way to make it stick and not crash/disrupt the editor?