UA 1232 then DL 5665 at Boston
Denver → Boston → Richmond
Timetable, Boston time
15:35UA 1232 from Denver at the gate
15:20DL 5665 to Richmond leaves the gate
23 h 45 apart on the timetable, overnight
DL 5665 leaves 23 h 45 after UA 1232 arrives on the timetable: more than half a day, so not a connection we count.