Email deliverability
How to roll DMARC out without breaking legitimate mail flow. SPF and DKIM prereqs, p=none through quarantine to reject, and how to read aggregate reports.
Email deliverability
An end-to-end view of mail-flow DNS — how MX, SPF, DKIM, DMARC, and DNSSEC interact, common misconfigs, and the dig commands to verify every layer.