Guides
Practical guides for DNS records, authentication, sender reputation, compliance, and inbox placement.
Guides
Practical writing on deliverability, business inboxes, and sending email from your product.
Run an email blocklist check the right way: look up each domain on Spamhaus, read DBL and ZEN return codes, and see why a clean result is not inbox placement.
Read articleDMARC policy checker guide: look up a domain's _dmarc TXT record, read the p=, sp=, rua= and t= tags, and see what a passing DMARC check does not prove.
Read articleInvestigate spoofed email using Authentication-Results, Received headers and DMARC reports, with an evidence checklist and incident response steps to follow.
Read articleSPF flattening fixes the 10-lookup limit but can break SPF when provider IPs change. Learn when it is safe and better options like pruning and subdomains.
Read articleDiagnose why Amazon SES Easy DKIM or BYODKIM verification fails or is revoked after DNS changes. Common provider pitfalls and ordered fixes.
Read articleLearn how to read raw email headers and check SPF, DKIM, DMARC and Return-Path results in Gmail, Outlook and Apple Mail, with annotated example headers.
Read articleA practical order for diagnosing email authentication failures: start with the Authentication-Results header, check SPF, then DKIM, then DMARC policy and alignment. Know when to stop and open a specialized guide.
Read articleReturn-Path is the receiver's copy of MAIL FROM. Bounces go there, not to From. An empty Return-Path marks a DSN, not a broken sender.
Read articleSES domain still pending? Check DEED first, then the three Easy DKIM CNAMEs at authoritative DNS. 72 hours is a ceiling, not a fix.
Read articleSPF PermError from too many DNS lookups means the record failed evaluation, not a temporary DNS blip. Remove unused mechanisms before flattening, and keep the apex under 10 lookups.
Read articleBuild a newsletter double opt-in flow with pending, confirmed, expired, and unsubscribed states. Send the confirmation; do not mail unconfirmed addresses.
Read articleLook up a domain’s MX hosts and map them to Google Workspace, Microsoft 365, Zoho, Fastmail, Cloudflare Email Routing, Arawa Mail, and common hosting. Practical provider fingerprints before you change MX.
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