When selecting "Display sender using address book", Quicksearch ignores the names displayed and searches only in the "real" From field. This is rather inconvenient: the option is very useful because a lot of people omit their real names in the From field (and sometimes makes unrecognizable their messages!), but being unable to search in the text actually displayed in the summary is a little confusing. Thank you very much for considering this improvement (if it is possible at all)!