Incidents
Email & DNS Incidents
What broke, who felt it, and what to check in your own stack — short write-ups with tools and fix guides linked.
Google & Yahoo DMARC enforcement
2026-03-19
Feb 2024 bulk-sender rules — 550 5.7.26 and minimum DMARC.
Yahoo bulk sender requirements
2026-03-19
Aligned with Google — PTR, DMARC, unsubscribe, spam rate.
Spamhaus public mirror sunset
2026-03-19
April 2026 — move to DQS or RBL queries go NXDOMAIN.
Microsoft 365 SPF / DKIM
2026-03-19
DKIM CNAMEs and Defender — SPF alone isn’t enough.
Subdomain takeover cases
2026-03-19
GitHub, S3, Heroku — dangling CNAME patterns.
Domain expiry outages
2026-03-19
When DNS stops — grace, redemption, prevention.
Email blacklist incidents
2026-03-19
Causes, list impact, recovery — Spamhaus to Postmaster.
SendGrid IP reputation
2026-03-19
Shared pools, domain alignment, dedicated IP tradeoffs.
DMARC adoption 2024
2026-03-19
Stats — growth vs stuck at p=none.
Typosquat phishing domains
2026-03-19
Lookalikes, homoglyphs, Typosquat Monitor.