That could be a little tricky because of where the field is in the table hierarchy. Is the u_submitted_by field on the Task or Change Request table? I'm assuming it is not on the Task table, otherwise you would be able to see it when you expand the "Approval for" field in the list:
I thought you could use a setting described here to allow the fields from the Change table to also appear -
http://wiki.servicenow.com/index.php?title=Personalizing_Lists#Adding_Extended_Fields_to_Base_Table_Lists. Unfortunately that does not work with that particular field type.
However, there is a trick you can use, by running the following Background Script to force that field in:
Note - be very careful when running Background Scripts as you can really mess things up if you are not careful.
(function(){
var gr = new GlideRecord("sysevent_email_action");
if (gr.get("sys_id of your email notification")) {
gr.recipient_fields = "sysapproval.ref_change_request.u_submitted_by";
gr.update();
}
})();
I tried it in demo022 and it works. The trick is the "ref_" before the "change_request" table name, telling the system the field is not on the Task table (sysapproval is a reference field to Task), but on the Change Request extended table.
