Incoming and Outgoing Email, filed by date, under “Pending and History Tabs” On the “Contact Screen”.
Pending Tab would contain all new outgoing email not sent and all incoming email not read.
History Tab would contain all new outgoing email sent and all incoming email read.
REASONING: You can easily go to the contact screen to find all old or new email for this particular contact under the “Pending or History tabs”. No searching for a particular email.