Email Deliverability

A business sends a customer update to 10,000 addresses, and its provider reports that 9,700 messages were accepted by receiving systems. Some of those may be in spam, so the 97% delivery rate does not establish 97% inbox placement.

A delivery metric usually counts messages not bounced or rejected, whereas deliverability asks more broadly whether desired recipients can actually receive useful messages. Opens and clicks can inform performance, but they are not exact proof of receipt or interest because tracking can be blocked or automated.

Authenticate domains, since SPF, DKIM and DMARC help receiving systems assess whether a sender is authorised, and follow current provider rules for the actual sending setup. Know every sender as well, because marketing software, invoicing tools and customer-support systems may all send from the domain, and an omitted service can fail authentication.

Maintain DNS carefully, since incorrect records can interrupt mail and changes should be tested rather than copied from another company's configuration. Respect consent, because sending campaigns to people who did not ask for them creates complaints and can damage future delivery.

Keep lists current, as invalid addresses cause bounces and old unengaged contacts can create risk, so use lawful, transparent list maintenance and offer an exit through a working unsubscribe process, since commercial mail may require one under local law and provider rules and requests should be honoured promptly. Watch complaint signals, because recipients marking messages as spam tell providers the material was unwanted, so investigate frequency and relevance.

Segment content, as billing notices and promotions serve different purposes and mixing them may confuse recipients and affect trust, and protect transactional mail, since receipts and account notices may be time-sensitive and their sending streams should stay reliable without promotional overload. Avoid sudden volume spikes, because a domain with little sending history may face extra scrutiny if it abruptly sends a large campaign.

Use a clear identity with a recognisable sender name and accurate address, never imitating another organisation, and write honest subjects, since misleading urgency can produce complaints even if the message technically reaches an inbox. Check technical errors, because server responses can distinguish temporary deferral from permanent rejection, and every retry should not be counted as a separate recipient.

Monitor reputation through provider dashboards that track spam rate, authentication and delivery problems, bearing in mind that coverage varies by mailbox provider. Test across recipients and compare cohorts: a test inbox can show formatting or routing problems but does not guarantee the whole list receives mail the same way, and deliverability can differ by domain, region or audience segment, so one campaign-wide number can hide concentrated failures.

Beware purchased lists, which raise both legal and operational risk because unknown contacts are more likely to complain or have invalid addresses, and review changes after migration, since a new provider, domain or IP can alter authentication and reputation, so monitor before scaling volume. Do not promise inbox placement, because receiving providers control filtering and users can move messages: Google's Gmail sender guidance lists authentication, spam-rate and message-format practices, and Mailchimp distinguishes inbox reach from bounces and spam placement, which illustrate current provider practice rather than a universal legal rule, while for an owner useful reporting separates accepted, bounced, spam-complained and engaged messages.