Z-Netz:                                               
                                                       
 [x]  Lower case user addresses in incoming            
      netcalls are converted according to Z-Netz       
      guidelines to upper case.                        
                                                       
 [ ]  Addresses are not changed.                       
                                                       
 There is no clear cut recommendation here. Probably   
 better is "on" ([x]), but then check that messages    
 from you to users with lower cases addresses (which   
 have then been converted to upper case) do get        
 through.