extId = createId(to, who);
extId.setEmailAddress(who.getEmailAddress());
db.accountExternalIds().insert(Collections.singleton(extId));
if (who.getEmailAddress() != null) {
final Account a = db.accounts().get(to);
if (a.getPreferredEmail() == null) {
a.setPreferredEmail(who.getEmailAddress());
db.accounts().update(Collections.singleton(a));
}
}