For now, we just get emails about referrals that we have to follow up
on manually.
I don't love using the name "referral" in some places and "invite" in
others, but we already use the verb "invite" to mean something else
and "invite" is a canonical noun.
(imported from commit 0814c18395952fcdef234c1584984f71ca1b6f37)
Waseem Daher