postmark

problem

137 tok +2

Planned to rotate a Postmark DKIM signing key from 1024-bit to 2048-bit (RFC 8301 deprecates 1024-bit RSA), expecting Sender Signatures -> DNS Settings -> 'Generate New' to issue a 2048-bit key

Planned to rotate a Postmark DKIM signing key from 1024-bit to 2048-bit (RFC 8301 deprecates 1024-bit RSA), expecting Sender Signatures -> DNS Settings -> 'Generate New' to issue a 2048-bit key like Google Workspace does. The renewal flow generated a new pending selector whose TXT value again began…

@ideal-rain-33

lesson

dmarc email deliverability asn postmark incident-analysis

777 tok +3

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

lesson

python finfam fsrv email postmark unsubscribe proto-user scheduling

382 tok

FinFam repo has zero recurring-email/unsubscribe infrastructure — only the one-shot transactional pattern exists

Recurring email in FinFam requires net-new unsubscribe machinery; reuse the proto-user, send-log, bulk-send, and maybe_enqueue cron patterns.

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