YYasir6d ago · 5 min readCatch-All vs Unknown Email Verification ResultsA catch-all result and an unknown result describe different kinds of uncertainty. Neither should automatically be treated as a confirmed, individual mailbox. A catch-all result indicates that a domainitsmeyasir.hashnode.dev
IIPYEOct 26 · 6 min readSending Email over IPv6: Reverse DNS, SPF, and Deliverability ChecksDisclosure up front: I run IPYE, a company that leases IP space. It gets one short paragraph at the end; the rest is plain networking. Email is the service where IPv6 most often goes wrong, because reipye-com.hashnode.dev
YYasirOct 24 · 5 min readHow to Verify an Email List Before Cold OutreachBefore you start an outreach campaign, check the email addresses you plan to use. An email verification tool can identify invalid addresses and flag other categories that need review, including dispositsmeyasir.hashnode.dev
DDaniel MoyaOct 18 · 2 min readThe 6 checks I run before sending a single cold emailYou wrote the email, picked the list, and hit send. A week later the replies are near zero and you can't tell whether people ignored you or never saw it. Usually it's the second one. Here's the checkl11Sdanimoya.hashnode.dev
ZZyVOPAug 16 · 12 min readHow We Built a Production Email Verification Pipeline That Saved Our Sender ReputationEvery platform that sends emails — onboarding sequences, notifications, password resets, newsletters — lives or dies by one metric: deliverability. Send a few dozen emails to dead mailboxes and your dblog.zyvop.com
KKishore BhavnanieAug 10 · 7 min readEmail Deliverability Beyond SPF, DKIM, and DMARCSPF, DKIM, and DMARC are the foundation of email authentication, and any organization serious about deliverability and anti-spoofing needs all three. But they are not the whole story. A newer set of sdnsassistant.hashnode.dev
RRachel SmithJul 27 · 4 min readCold Email Deliverability Checklist (2026)Originally published on agentgtm.app. The 10 checks we run before any campaign sends. Authentication, warmup, verification, pacing, and recovery. Deliverability is binary: your email lands in the inbo11Sagentgtm.hashnode.dev
EevgeniJul 20 · 2 min read83.4% of the web's email runs on just 3 providersBy the team at MailTester Ninja, a real-time email verification API that stores nothing. Across 50,000 domains, mail hosting is strikingly concentrated: Top 1 provider handles 32.4% of mail-enabled dmailtester.hashnode.dev
EevgeniJul 16 · 2 min readWho actually enforces DMARC? Reject rates by email providerBy the team at MailTester Ninja, a real-time email verification API that stores nothing. DMARC enforcement isn't spread evenly, it tracks who hosts the mail. Share of each provider's domains that reacmailtester.hashnode.dev
SSapotaCorpMay 24 · 4 min readSFMC Email Frequency and Spam Filters: Send Enough, Not Too MuchA retail client we advised decided to quadruple email frequency - from one send per week to four - believing more sends would mean more revenue. Within a month: Unsubscribe rate tripled. Complaint rasapotacorpvn.hashnode.dev
