Writing that delivers.
Deliverability guides and product notes — no filler.
The best ZeroBounce alternatives in 2026, compared
Looking for a ZeroBounce alternative? A fair comparison of the best email verifiers on price, catch-all honesty, EU data, and API — with sourced facts.
Emails going to spam in Outlook: the causes and fixes
Emails going to spam in Outlook? How Microsoft's reputation filtering works, plus SNDS, JMRP, and the fixes that move Office 365 mail to the inbox.
How to set up DMARC: the safe, step-by-step rollout
How to set up DMARC the safe way: publish the TXT record at p=none, read the aggregate reports, fix SPF and DKIM alignment, then enforce with reject.
One-click unsubscribe: the header pair Google now requires
One-click unsubscribe is the List-Unsubscribe header pair (RFC 8058) Google and Yahoo require on bulk mail. What it is, why it matters, and how to add it.
Spam complaint rate: the number that decides deliverability
Your spam complaint rate is complaints divided by delivered mail. Learn the 0.3% limit, the 0.1% target, and how to measure and reduce complaints.
Email verification API comparison for developers
How to choose an email verification API: verdicts and evidence, sync vs async, bulk and webhooks, rate limits, EU data — and the options compared.
Spam trigger words: the myth vs what filters weigh
Spam trigger words are mostly a myth: modern filters weigh reputation, authentication and list quality far more than any word in your copy.
The Barracuda blacklist (BRBL), explained and delisted
The Barracuda blacklist (BRBL) lists IPs with poor sending reputation. How to check, request free removal, and stay off it for good.
Proofpoint Dynamic Reputation and why enterprise mail gets blocked
Proofpoint Dynamic Reputation (PDR) blocks mail only to enterprise inboxes. How the Proofpoint blacklist works, and how to check and fix it.
Cold email deliverability: how to reach the inbox
Cold email deliverability is hard: no engagement and dirty lists. The levers that get cold outreach to the inbox — starting with verification.
SpamCop blacklist: how it lists and self-clears
The SpamCop blacklist (SCBL) lists sending IPs from spam reports and traps, then expires on its own. How it works, how to check, and how to get off.
The UCEPROTECT blacklist and its three levels, explained
How the UCEPROTECT blacklist's three levels work, why you can be listed through no fault of your own, the free-wait vs paid-express debate, and more.