The ZevSend blog
Deliverability, email infrastructure, and the edge cases that break transactional messaging in real products. Written by the people building ZevSend.
Fourteen production failure modes that never show up in testing: retry duplicates, late OTPs, alignment failures, the Gmail and Yahoo thresholds, bounce handling done backwards, and the it-works-in-testing trap.
DAN 
A four-level ladder from local capture servers to sandboxed providers and stranger-proof staging, plus the five email assertions that actually catch production bugs.
DAN 
Verification, resets, receipts, dunning, invites, security alerts: the twelve transactional emails no product escapes, what belongs in each one, and the production failure each one is known for.
DAN 
The four DNS records behind every email your product sends, explained with one mental model, real record examples, and the failure modes that put authenticated mail in spam anyway.
DAN Sections
ZevSend is a developer API for transactional email, SMS, WhatsApp, and verification codes. Free plan, sandbox mode, and DNS records we generate for you.
