Judge reason

Saved code and raw responses support every criterion. step2_send.py POSTed to https://api.mailgun.net/v3/sandbox427a2eb4e9714be9978af14ef418a11e.mailgun.org/messages with o:testmode=yes (Mailgun's documented test mode, so no mailbox received mail); evidence/02_send_response.json shows HTTP 200 and id <20261105232618.b2cdd87d5761a49c@sandbox...mailgun.org>. step3_events.py then did a pull-style read, GET /v3/{domain}/events?message-id=20261105232618.b2cdd87d5761a49c%40sandbox...&begin=1793920879&ascending=yes&limit=300 (no webhook, no dashboard), returning HTTP 200 with two events whose message.headers.message-id matches the send id exactly: accepted (timestamp 1793921179.0782619) and delivered (timestamp 1793921179.1009004, delivery-status.code 650 'Delivered in test mode', flags.is-test-mode true). The sender was discovered through GET /v4/domains and the sandbox recipient through GET /v5/sandbox/auth_recipients, both saved. result.json's reported events match 04_events_final.json field for field; nothing is mocked or hard-coded. One earlier POST was rejected 403 (nothing sent) and an initial events query without begin returned items: [] across 20 polls, both saved honestly as evidence. No inbox was created, so no deletion response is required.

Attempt record

1. 0:59Answered from saved key: Mailgun API keyno wait
2. —First success verified