Digital marketing term
SMTP
The protocol that hands email from one server to another; newsletters and transactional mail leave through this layer. Bad authentication or a blocklist can tank inbox placement without a visible send failure.
Detailed explanation
This is how a sending server talks to a receiving server. Marketing newsletters, order confirmations, and password resets all ride this family of protocols. The From line users see is proven with SPF, DKIM, and DMARC — not by the transport protocol alone.
Common mistakes: blasting volume from a cold shared IP, spoofing From domains, or mailing scraped lists. The receiving host then junks or rejects the message. Consent-less form dumps are both a legal and a deliverability problem.
Watch delivery rate, bounces, complaints, and spam-folder placement. Split transactional mail from promo streams, keep DNS auth clean, and prune bad addresses. The protocol can succeed while the inbox still never shows the message.
Frequently asked questions
- Why do newsletters land in spam?
- Cold IPs, weak SPF/DKIM/DMARC, high complaint rates, or purchased lists. The protocol can connect and still lose the inbox filter.
- Do SPF and DKIM replace this protocol?
- No. SMTP moves the message. SPF, DKIM, and DMARC prove the sender is allowed to use that domain.
Related terms
Internal links for the topic cluster — read these concepts together.
- Email MarketingSending news, offers, or teaching through a permissioned list you own. It is not a rented blast; it stands on delivery, relevance, and an easy way out.
- DeliverabilityDeliverability is the email marketing concept that describes the rate at which sent emails reach a recipient's actual inbox rather than a spam folder, along with the factors behind that process.
- DatabaseThe structured store for records: users, orders, content, and subscriptions. In marketing, “the list” is usually a view of this store, not a spreadsheet.
- HostingThe service that keeps a site’s files, database, and mail on a machine reachable from the internet. A domain does nothing until DNS points it at that server.
- DomainThe name people type and see in the address bar: brand word plus extension. Email, TLS, and canonical URLs hang off it; swapping it on a whim splits every signal.