Pluto P3 residual: bulkInviteUsers welcome-email loop bypasses the /send-email HTTP rate limiter (PLUTO-20) — uncapped in-process sends on bulk invite. Decide cap (e.g. 100/batch or inter-send delay) vs accept (admin-initiated, low-freq, in-process-mail-undroppable per PLUTO-20 design). From audit round-1.