I have  a custom object  called Issue , Following fields  Issue assigned to its a pick list values with user names only Like Kiran , Kumar , Sundar and I have another picklist called Issue Type Picklist should be fired to indivdual user based on the Picklist value example if issue type equals not working broad band Issue that email should be sent to the user.

I know that by making the assigned to picklist can be changed to user look up but the problem here is I already have a user look up named as encountered by , so when ever i am trying to send email notification its not taking the email address of the user look up  so tats one of my concern

can anyone suggest a email notification should be fired based on the pick list to the indival user