Best practices, tutorials, tips and tricks to maximize your email marketing results.
182 articles
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Sendinblue (now Brevo) is convenient at low volume and expensive at scale. For high-volume bulk email, a flat-rate dedicated SMTP server is usually the cheaper alternative.
When a message cannot deliver right now, it waits in a queue and retries on a backoff schedule. Here is how queues, deferrals and retry logic work.
IP reputation and domain reputation are scored separately by mailbox providers. A new domain on a new dedicated IP needs both warm-ups, here's what each one covers.
Relay access denied looks scary but has only four root causes. This guide maps each scenario, sending vs receiving, port 25 vs 587, to its exact config fix.
A PTR record maps your sending IP back to a hostname. Without one, Gmail rejects your mail outright. Here's who sets it, how, and how to verify FCrDNS.
Postmark is premium, fast, and easy; SES is cheap and raw. Here is exactly when each one wins for transactional email, and where a dedicated SMTP server fits.
When your list crosses six figures, per-subscriber ESP pricing hurts and shared pools throttle. Here's the SMTP setup newsletter publishers use to send big and land in the inbox.
Single opt-in adds subscribers the moment they hit submit. Double opt-in waits for a confirmation click. One grows faster, the other protects your sender reputation. Here's the real trade-off.
Gmail's 421 4.7.28 means your IP is sending faster than its reputation allows. It's temporary, not a hard block. Here's why it happens and how to clear it.
