Domain vs IP reputation in 2026: how Gmail and Yahoo shifted the weighting toward domain in 2024, how each is measured per receiver (Postmaster Tools, SNDS, Sender Score), portability (domain ...
IP warmup schedule for 2026: complete 30/60/90 day volume ramp with exact daily numbers, engagement tier segment selection (7d/30d/60d/90d), KPI checkpoints (bounce, complaint, delivery, open rates), ...
Suppression lists best practices covering schema design (normalization, scope, source tracking), the three signal sources (bounces, complaints, unsubscribes), storage patterns (self-hosted vs ...
Feedback Loops (FBL) complete guide covering the ARF format (RFC 5965), signup process for Google Postmaster, Microsoft JMRP, Yahoo, Comcast, and La Poste, per-provider coverage, ARF parsing code in ...
Bounce categorization guide going beyond hard vs soft. Covers the five practical categories (address, mailbox, policy, content, technical) plus complaint, how to derive them from RFC 3463 enhanced ...
DSN parsing complete guide covering RFC 3464 multipart/report structure and RFC 3463 enhanced status codes X.Y.Z. Explains the three DSN parts, all delivery-status fields (Reporting-MTA, ...
The List-Unsubscribe header (RFC 2369) and List-Unsubscribe-Post header (RFC 8058) enable the one-click unsubscribe that Gmail and Yahoo require from senders above 5,000 messages per day since ...
SPF has a hard 10 DNS lookup limit per evaluation (RFC 7208). Exceed it and you get PermError, breaking DMARC alignment. Flattening replaces includes with raw IPs to work around the limit, but ...
DMARC has three policies: p=none (monitor), p=quarantine (route to spam), and p=reject (refuse entirely). This guide covers the roll-out roadmap, how long to stay at each stage, what to watch in ...
A single domain sending from Mailgun, Mailchimp, Workspace and other ESPs needs a separate DKIM selector for each sender. This guide covers the selector concept, step-by-step setup for a 3-ESP ...
ARC (Authenticated Received Chain, RFC 8617) lets mailing lists, forwarders and gateways preserve authentication results when they modify messages in ways that would otherwise break DMARC. This guide ...
BIMI displays your brand logo next to authenticated emails in Gmail, Yahoo, Apple Mail and other providers. This guide covers what BIMI does (and doesn't do), the DMARC and SVG prerequisites, the ...
