Learn
Email deliverability, explained by practitioners
Guides sourced from RFCs, postmaster documentation, and operator data — dated, maintained, and honest about what nobody can measure.
Domain warmup
How new domains earn a sending history, and how long it really takes.
How long to warm up an email domain before a campaign?Nine published ramp schedules converge on 3–6 weeks, and M3AAWG says plan for six. What the evidence says — and why day one is the most dangerous.8 min readHow to warm up an email domain: a step-by-step guideStep-by-step domain warmup: DNS prerequisites, a week-by-week ramp built on published ESP schedules, monitoring gates, and mistakes that reset progress.10 min readFree email warmup: what actually works without payingFree email warmup is real: manual sending, free tool tiers, and free plans compared honestly - plus the hidden costs and what paying actually buys.8 min readEmail warm up tools: an honest comparison (2026)Peer-network mailbox warmers vs ESP-native domain warming: pricing from $19 to $96 per mailbox, how each model works, and what the evidence doesn't show.9 min readNew Domain Blocklisted? It's Probably Spamhaus ZRD, Not YouSpamhaus ZRD lists every new domain for its first 24 hours, with no delisting. How to read the return codes and tell policy apart from a real listing.8 min read
Troubleshooting deliverability
Why mail lands in spam, and how to find the actual cause.
Why are my emails going to spam? A diagnostic walkthroughThe real causes in likelihood order - PTR records, SPF/DKIM/DMARC, spam rate, reputation, list quality - with a concrete check and fix for each.9 min readWhat is a PTR record? Fixing Gmail's 550 5.7.25 email errorPTR records explained: what reverse DNS is, why missing PTRs became Gmail's top rejection cause, and how to fix error 550 5.7.25.9 min readHow to improve email deliverability, in order of impactA practitioner checklist for improving email deliverability, ordered by real impact, with a verify step for each fix — and the folklore that wastes time.10 min readCold email deliverability: the complete guide for 2026Why cold email needs its own domain, the 0.3% spam-rate math, content fingerprinting, the SMTP errors that matter, and what to do when a domain burns.11 min readDo You Need an Email Deliverability Consultant?Most deliverability problems are diagnosable in an afternoon with free tools. When a consultant is genuinely worth hiring — and the red flags to avoid.8 min read
Reputation & measurement
How mailbox providers score you, and how to see what they see.
Google Postmaster Tools: The Complete 2026 GuideHow to set up Google Postmaster Tools, read each 2026 dashboard, and what to watch now that the Domain and IP Reputation charts are gone.9 min readDomain Reputation vs Domain Authority: Not the Same ThingEmail domain reputation and SEO Domain Authority share a name and nothing else. What each one measures, who scores it, and why a high DA won't fix spam.8 min readInbox Placement Rates 2026: The Numbers Worth TrustingInbox placement rates by provider and region — Gmail 89.8%, Microsoft 77.4% — plus the famous email statistics you should stop citing.10 min readEmail Deliverability Tools: The Honest 2026 StackThe email deliverability tools that matter in 2026, by job: reputation dashboards, DMARC analyzers, blocklist monitors, seed tests. Free options flagged.10 min read
Setup & compliance
DNS, authentication, and the law — getting the foundations right.