Comprehensive guides for infrastructure architecture, perimeter vulnerability mitigation, SMTP transport compliance, and authoritative DNS resolution.
Mitigating evaluation errors caused by exceeding 10 DNS lookups. TXT record flattening strategies and SaaS subdomain delegation.
Domain-based message authentication protocol, RUA/RUF reporting, and progressive policy migration from none to reject without traffic loss.
Mandatory requirements for senders of more than 5,000 daily emails: FCrDNS resolution (PTR), one-click unsubscribe, and spam rates below 0.3%.
Preventing Man-in-the-Middle attacks and STARTTLS downgrade on SMTP channels via HTTPS .well-known policies and aggregated TLS-RPT reports.
Configuring reverse PTR records matching HELO/EHLO headers and mail server banners to pass strict anti-spam filters.
Preventing Single Points of Failure (SPOF) through geographic NS server distribution across BGP networks and disjoint Autonomous Systems (ASN).
Authenticating encryption keys within the DNS system to protect SMTP traffic via TLSA records and zone signing using RRSIG and DS.
Identifying and remediating DNS pointers to removed resources in AWS S3, GitHub Pages, or Azure to prevent subdomain hijacking.