I think the whole point of this was to see if the "agents" could act like a real human and real humans use Gmail much more frequently than sendmail. Sage even commented that they had update their prompt to tell the agents to not send email and not just remove the Gmail component for fear that the agent would just open it's own Gmail (or Y! mail, etc.) account and send mail on it's own.
This whole idea is ill-conceived, but if you're going to equip them with email addresses you've arranged by hand, just give them sendmail or whatever.