How to Improve Email Deliverability

Business email volumes have climbed each year for over a decade, yet acceptance rates do not rise automatically alongside that curve. Anti-abuse algorithms assess identity, origin, cryptographic signature, policy intent, and historical behaviour. A sender cannot buy their way into trust. Better inbox outcomes emerge when a domain owner aligns authentication, DNS signalling, and enforcement. That means the work starts at the domain layer before subject lines or CTAs. Providers reward organised senders who prove identity at the DNS layer.

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 operates like a permission register. It tells receivers which IP addresses or systems are authorised to originate mail for a domain. That solves one problem very directly: anyone who attempts to impersonate the domain from an unauthorised host becomes mathematically invalid.

We must produce a record that is both accurate and lean. A complex SPF chain with a dozen include statements harms performance because DNS lookups take time. Google’s public documentation mentions that receivers can reject SPF when the evaluation chain exceeds 10 lookups. Therefore, keep SPF narrow and reference only legitimate mail systems.

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, bounce rate rises. It is a surgical discipline, not guesswork.

DKIM gives cryptographic proof

DomainKeys Identified Mail is the missing half of the identity chain. SPF only declares the envelope origin. DKIM signs the message content. Receivers then verify the signature by reading the public key we publish in DNS as a TXT entry under a selector.

This system makes mail tamper-evident. If a hostile actor modifies a message body or subject line, the signature breaks, and receivers treat that tampering as a red flag.

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

Better deliverability is not mysterious. It is the natural outcome of protocol obedience, policy enforcement, disciplined configuration and constant observation. SPF gives permission, DKIM gives mathematical proof, and DMARC converts both into declared behavioural intent. When that triad consistently aligns, mailbox providers recognise structure and respond positively. Then, reputation monitoring safeguards that posture across time. In short, DNS-level governance is the nervous system of modern mail. If a sender treats it seriously, inbox acceptance no longer feels random.