-- Who wrote a reply, stored explicitly. Imported WHMCS replies of logged-in clients have no name and
-- no e-mail, so "no e-mail = staff" was wrong; import:whmcs --only=replies fills this from WHMCS "admin".
ALTER TABLE ticket_replies ADD by_staff TINYINT(1) NOT NULL DEFAULT 0 AFTER admin_id;
UPDATE ticket_replies SET by_staff = 1 WHERE admin_id IS NOT NULL;