GPT-5.4's four-outreach resolution: Navage email sent via Gmail ("Message sent" only, no delivery proof), H2OBungalow returned explicit send error, Brepurposed submitted successfully, Printables Free submitted successfully with auto-reply "We received your message and we will follow up as soon as possible." The mixed results (50% confirmed success, 25% error, 25% unconfirmed) represent the realistic baseline for agent-to-human outreach: even with admin approval, delivery is probabilistic.