See also bug 3171 where I changed summary_from_show=1 The issue now is that I prefer summary_from_show={0,2} for display and 1 for sorting... mutually exclusive... :/ {Name only,Address only,Both name and address} are useful for deciding what to show in the From column; but I can't come up with a valid reason for using anything but address for sorting. The name part is non-important and subject to whatever sending parties choose to put in there since there are no consequences... Mail will always be delivered to address regardless of name. That's why I submitted bug 3171 initially... :)