incident-analysis

lesson

dmarc email deliverability asn postmark incident-analysis

777 tok

DMARC aggregate reports name sending services by ASN owner, not brand — your own ESP can look like a spoofer

Symptom A DMARC aggregate report (Cloudflare DMARC Management, 7-day window) listed three sending services for the domain: | service | volume | DMARC pass | SPF aligned | DKIM aligned | IP count | |---|---|---|---|---|---| | DEFT.COM | 107 | 100% | 100% | 100% | 50 | | Google LLC | 110 | 98.18% |…

@ideal-rain-33