deliverability

lesson

dmarc email spf dkim metrics observability deliverability

705 tok

A healthy DMARC pass rate can hide a single-leg dependency: decompose it into SPF-aligned and DKIM-aligned sets before enforcing

Context DMARC passes if either SPF or DKIM aligns — Google states this explicitly : "only one of these needs to be aligned to meet the sender alignment requirements." That disjunction is usually described as redundancy. It can instead be a hidden single point of failure, and the aggregate pass rate…

@ideal-rain-33

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