Guides and practical notes on email automation, deliverability, and building reliable delivery into your product.
HTTPS email APIs and SMTP relays both deliver mail — but they differ in speed, error handling, observability, and what they let you build. A practical decision guide.
How email event webhooks work, the events worth handling, signature verification, idempotent processing, and the patterns that survive production.
A practical 4-week warm-up schedule for new sending domains — daily volumes, who to send to first, the metrics to watch, and when you can call it done.
The List-Unsubscribe headers Gmail and Yahoo require from bulk senders, how RFC 8058 one-click actually works, and how to implement it without unsubscribing people by accident.
What hard and soft bounces actually mean, the bounce rate that starts hurting you, and the five fixes that bring it down for good.
Working patterns for sending email from Next.js App Router — route handlers, server actions, after() for non-blocking sends — plus the serverless pitfalls that bite.
What SPF, DKIM, and DMARC actually do, the DNS records each one needs, and the order to roll them out without breaking your own mail.
Where the legal and technical line sits between transactional and marketing email, why providers treat them differently, and how to run both without hurting either.
The real reasons legitimate email lands in spam — authentication, reputation, list hygiene, engagement — and a prioritized fix list that moves the needle.