InboxGuards Email Test: Email deliverability and security report for a real email you sent. 1) POST /v1/tests (free) for a one-time address + read token. 2) Send one real email to it. 3) GET this with ?test_id= and X-Read-Token. Report: SPF, DKIM (key size, alignment), DMARC, ARC, BIMI, sending IP rDNS + SpamCop, MTA-STS/TLS-RPT, one-click unsubscribe, headers, content, 0-100 score, top fixes. Not-ready/unknown tests: 4xx, never charged.