How to Improve Email Deliverability

Despite the increase in business email volume for the past ten years, the rate of acceptance has not increased correspondingly. The algorithms that fight abuse consider identity, receipt origin, cryptographic signature, policy purpose, and behaviour. The sender does not have the capacity to purchase their way to being trusted. The best results will be produced if the domain owner coordinates their authentication, DNS, and enforcement policies. The process begins at the domain level, even before the subject line and button. Providers will reward organised senders if they authenticate their identity on the domain level.

In this post, you will learn how to maximise email deliverability by implementing some of the best practices with DNS and email server configuration.

Anchor identity around SPF

Sender Policy Framework is a kind of ‘permission register.’ It shows recipients the IP addresses or servers that are authorised to send messages from a certain domain. That is one problem solved very simply. Anyone who tries to spoof messages from that domain on an authorised server is mathematically meaningless.

We must provide an accurate and concise record. An SPF chain that contains an include statement in each of a dozen records defeats performance since DNS fetches take time to respond. According to Google’s official documentation, recipients disfavour SPF if it takes over 10 lookups to complete the chain. Hence, an SPF record should always be short and only include legitimate mail servers.

Example structure:

v=spf1 a mx ip4:203.0.113.12 include:esp-provider.example ~all

That SPF syntax means: local A record hosts count as valid, the declared MX target counts as valid, the specific IPv4 backend counts as valid, and a named email service provider counts as valid. Everything else fails.

SPF must be reciprocal with actual reality. If we authenticate a host that we never use, we weaken the trust model. If we forget to authenticate a system that we use, the bounce rate rises. It is a surgical discipline, not guesswork.

DKIM gives cryptographic proof

DomainKeys Identified Mail is the missing link in the identity chain. SPF specifies mail envelope sender origins. DKIM verifies the content of the mail. The receivers can then use the public key that we publish in DNS records in the form of a TXT resource record against the selector.

Such an infrastructure ensures that the mail is tamper-proof. Any malicious party altering the body or subject of the mail will cause the signature to be defective, signalling the recipients to flag such mail.

Avoid short keys. A 1024-bit key forms a baseline. If your panel allows 2048-bit DKIM keys, use them. Attackers escalate computing power each year, so cryptographic margin matters.

Audit DKIM periodically. Many senders deploy DKIM once and never verify the signature again. But some hosting providers rotate infrastructure silently, and DKIM selectors can expire. A diagnostic platform that reads headers and interprets DKIM alignment will show you whether your signatures verify cleanly or whether they degrade.

DMARC converts authentication into policy

DMARC sits above SPF and DKIM. It does not sign or authorise anything itself. It acts as a policy engine that tells receiving systems how to react when SPF or DKIM do not align.

A typical DMARC record includes these core directives:

• policy (none, quarantine, reject)
• rua (aggregate report mailbox)
• ruf (forensic mailbox, optional)
• alignment strength (relaxed or strict)

Policy escalation should be gradual. Start with monitoring mode first, then enforce. That approach reflects how large senders harden domains without surprising legitimate routing paths.

Example serial progression:

p=none  (observe)
p=quarantine  (risk intervention)
p=reject  (hard stop spoofing)

When organisations reach reject, spoof attempts collapse because receivers receive explicit instructions. That pushes trust upward, and inbox placement improves because the domain demonstrates responsible stewardship.

Align these three pillars together, not in isolation

SPF, DKIM, and DMARC share a symbiotic relationship. SPF without DMARC is incomplete. DKIM without DMARC is incomplete. DMARC without SPF or DKIM yields limited value because there is nothing to enforce.

The highest deliverability uplift appears when alignment is strict, records are lean, and DNS resolves rapidly.

Cold outreach agencies learned this sharply over the past two years. Numerous reports showed that campaigns with strict alignment outperformed non-aligned campaigns by measurable margins. This confirms a broader truth: receivers reward domains that self-govern.

Treat bounce management as a hygiene routine

Bounce handling is not a one-time task. Improper bounce handling destroys reputation more reliably than poor copy quality. Remove hard bounces immediately. Limit soft bounces to three attempts. Keep the list lean. A clean list is a strong brand signal.

Warm both the domain and the IP

Domain history matters. If the domain is new, avoid high-volume sending early. If the IP is shared, adopt the role of a model citizen. Shared IPs behave like shared classrooms. If one sends garbage, everyone suffers. If the pool is healthy, protect it. If the pool is unhealthy, request a different sending pool. That request alone can rescue a sinking reputation.

Conclusion

Improved deliverability is no secret. It’s the result of protocol compliance, policy enforcement, controlled configuration, and vigilant monitoring. “SPF grants permission, DKIM demonstrates proof, and DMARC translates both into stated behavior.” When these three elements are in harmony, mailbox providers see structure and deliver positively. Reputation monitoring then protects that reputation over time. “DNS-level management is the ‘nervous system’ of modern mailing.” When a particular sender takes DNS-level management seriously, “acceptance isn’t a matter of chance.”