Using an API to Enrich Threat Intelligence With Email Trust Signals

Threat intelligence becomes more useful when an indicator carries context, not just a domain name or IP address. Email sender trust signals can help security teams distinguish an established business domain from a newly registered lookalike, a misconfigured sender, or an address frequently associated with spoofing risk.

Trusted Sender Score provides domain reputation checks, DKIM and DMARC tools, anti-spoofing resources, bulk verification, and developer access. An API integration can add these indicators to a security information and event management platform, phishing triage process, or internal threat feed without requiring analysts to check every domain manually.

Define The Enrichment Objective

Start by deciding which events should trigger a lookup. Common candidates include a suspicious sender domain found in a reported email, a domain extracted from a malicious URL, or an indicator received through a commercial intelligence feed. Filtering before enrichment prevents unnecessary requests for harmless or well-known infrastructure.

The result should answer a practical question: how much confidence should the organisation place in this sender domain? Useful fields may include the trust score, domain reputation, registration age, DKIM status, DMARC policy, spoofing exposure, and the time of the last check. Treat these indicators as risk context rather than a final verdict.

Connect The API Securely

Create a dedicated API credential for the integration and store it in a secrets manager rather than in a script, ticket, or source-control repository. Limit access to the service account that performs enrichment, and rotate credentials according to the organisation’s security policy. Log request outcomes without recording secrets or unnecessary message content.

API specifications can change, so confirm the current authentication method, endpoint names, response schema, quotas, and supported lookup formats in the Trusted Sender Score developer documentation or account interface. Build the connector around configuration values instead of hard-coding assumptions, particularly when operating across a security team in Sydney and an incident response group in Melbourne.

Map Trust Data To Threat Records

A useful enrichment record preserves the original indicator and adds clearly named fields. For example, a domain object might contain trust_score, dmarc_policy, dkim_present, spoofing_risk, registration_age_days, checked_at, and source. Retaining the source and timestamp makes later investigations easier when a domain’s reputation changes.

Map the response into the format already used by the threat platform, such as STIX objects, a SIEM entity, or a case-management attribute. Keep unknown, unavailable, and negative results distinct. A missing DMARC record is different from a record that explicitly publishes a restrictive policy, and an API timeout should never be interpreted as a safe result.

Interpret Authentication Signals Carefully

DKIM and DMARC are valuable indicators, but authentication alone does not prove that a sender is legitimate. A criminal can authenticate mail from a domain they control, while a genuine Australian business can have imperfect records because of marketing platforms, help desks, or forwarding services. Combine authentication status with reputation, age, observed behaviour, and message context.

Forwarding can also distort reporting. Australian organisations using shared mailboxes or outsourced services may see legitimate messages pass through several systems before reaching a recipient. When a DMARC report shows an unexpectedly high proportion of forwarded messages, the forwarded email checklist can help analysts separate delivery architecture from impersonation activity.

Handle New And Suspicious Domains

Newly registered domains deserve additional scrutiny, especially when they resemble a bank, government department, university, or well-known retailer. A domain using a familiar brand with a different top-level domain, altered spelling, or added suburb name can look plausible in a busy inbox. This is relevant to campaigns targeting customers in Brisbane, Perth, and other Australian population centres.

Use age and naming similarity as risk multipliers rather than automatic blocking rules. A legitimate start-up may use a recently registered domain, while an older domain can still be compromised. For a structured assessment of an unfamiliar sender, apply the new domain tips alongside mailbox, URL, and endpoint evidence.

Add Resilience To The Pipeline

Threat-feed enrichment should continue operating when a provider is slow or temporarily unavailable. Set connection and response timeouts, use bounded retries with back-off, and place failed lookups in a queue for later processing. Cache results for a defined period, while allowing urgent investigations to request a fresh check when appropriate.

Respect published rate limits and avoid sending the same domain repeatedly from multiple tools. Normalise case, remove trailing dots, and validate internationalised domain names before lookup. For organisations operating across AEST, ACST, and AWST, store timestamps in UTC and display local time only at the analyst interface.

Use Results In Australian Security Operations

A practical workflow can enrich an alert when a staff member reports suspected phishing, then raise its priority if the sender has a poor trust score, missing authentication, or strong spoofing exposure. Security teams can combine these findings with Microsoft 365 telemetry, secure email gateway logs, DNS data, and indicators from the Australian Cyber Security Centre.

The anti-spoofing guidance can support detection and policy reviews when an organisation wants to reduce impersonation risk. Keep personal information out of enrichment requests wherever possible, and assess retention against the Privacy Act and internal governance requirements. Used this way, sender trust becomes a repeatable signal that improves triage while leaving final decisions with trained analysts.