Digital Lexicon Hub

The ability of sent email to reach recipients' inboxes instead of being rejected, filtered to spam or silently dropped by mailbox providers.

Emails that land in spam generate no revenue, so deliverability sets the ceiling for every campaign, nurture flow and cold outreach program, and a damaged domain reputation can take weeks to recover.

Before a launch, a team authenticates its sending domain with SPF, DKIM and DMARC, removes contacts with no engagement in 12 months, adds one-click unsubscribe headers and uses Google Postmaster Tools to keep spam complaints under 0.1%.

Delivery rate in a sending tool counts accepted messages, not inbox placement, and open rates are unreliable because of privacy features. Mailbox providers do not publish their filtering logic, so good practice improves odds but cannot guarantee inbox placement.

Mailbox providers weigh authentication through Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM) and DMARC, plus IP and domain reputation, engagement and complaints. Gmail requires senders of about 5,000 or more daily messages to personal accounts to pass SPF and DKIM, publish DMARC with at least p=none, align the From domain, use TLS, support one-click unsubscribe under RFC 8058 and keep spam rates below 0.3%. Yahoo sets similar rules.