Automate Domain Trust Checks in Your SIEM
Security teams often investigate suspicious messages under time pressure. A domain reputation lookup can add useful context, but manually checking every sender, domain, DKIM record, and DMARC policy does not scale across a busy SOC.
Trusted Sender Score provides an API that can turn those checks into repeatable enrichment. By connecting domain trust verification to your SIEM, you can evaluate indicators automatically, attach authentication results to alerts, and prioritize investigations involving spoofing or phishing.
Define The Detection Objective
Start by deciding which events should trigger a trust check. Common sources include secure email gateways, Microsoft 365 or Google Workspace alerts, phishing-report mailboxes, threat-intelligence feeds, and endpoint detections containing a suspicious domain.
The input should be normalized before it reaches the API. Extract the registrable domain rather than sending an entire email address or URL, remove surrounding punctuation, convert it to lowercase, and reject malformed values. This prevents duplicate lookups and reduces unnecessary API traffic.
You may also want to distinguish between a sender domain, a return-path domain, and a URL domain. These values can differ in a spoofing attempt, so preserving each field gives analysts a clearer view of the attack path.
Prepare Authentication And Access
Create a dedicated integration identity for the SIEM rather than using a personal credential. Store the API key or token in a secrets manager, restrict access to the automation service, and rotate credentials according to your organization’s security policy.
Use the authentication method, request format, endpoint, and rate limits documented for your Trusted Sender Score account. Treat those details as configuration rather than hard-coded logic. This makes it easier to update the connector if the API version or authentication scheme changes.
A production integration should also define timeouts, retry limits, and behavior for unavailable responses. A failed reputation lookup should produce an observable “unknown” result, not silently classify a domain as safe.
Build The Enrichment Workflow
A practical workflow begins when the SIEM receives an event containing a domain. The automation extracts the indicator, checks a short-lived cache, and calls the platform only when a fresh result is needed. The returned trust information is then written back as event fields or an enrichment record.
Useful fields can include the domain, trust or reputation result, lookup timestamp, DKIM status, DMARC status, spoofing indicators, and a link or reference to the original investigation. Preserve the raw response where permitted, but create concise normalized fields for searches and correlation rules.
For human-led triage, context matters. A domain reputation score should support investigation rather than replace it; analysts can also review this guide to cold email sender trust when a message appears unusual but has not triggered a definitive detection.
| SIEM Stage | Automation Activity | Security Value |
|---|---|---|
| Ingestion | Capture sender, return-path, and URL domains | Preserves useful indicators |
| Normalization | Validate and canonicalize domain names | Avoids duplicate or malformed lookups |
| API Enrichment | Request current trust and authentication data | Adds reputation and email-security context |
| Correlation | Combine results with message and user events | Improves phishing detection |
| Response | Tag, alert, quarantine, or escalate | Turns intelligence into action |
| Auditing | Record request status and timestamps | Supports troubleshooting and compliance |
Map Results To Risk Decisions
Avoid building a rule around a single score. A recently registered or unfamiliar domain may be legitimate, while a compromised established domain may have a good historical reputation. Combine the API result with message authentication, sender behavior, URL analysis, user reports, and threat-intelligence matches.
For example, a high-priority alert could require several conditions: a failed DMARC alignment, a suspicious sender domain, a low trust result, and a message delivered to multiple employees. A lower-severity event might simply tag an unfamiliar domain for analyst review.
Keep the original result separate from your internal risk rating. This preserves the distinction between the platform’s assessment and your organization’s decision logic, making detection rules easier to tune and explain.
Handle Scale, Errors, And Privacy
Caching is important when the same domain appears in many messages. Set a retention period that reflects how quickly your organization needs fresh results, and avoid querying repeatedly during an email flood. Respect published API limits and use controlled backoff for temporary failures.
Bulk checking can help with scheduled reviews of supplier domains, monitored brands, or historical mail data, while real-time calls are better suited to high-value alerts. Developer tools and API capabilities can also support separate workflows for onboarding, threat hunting, and security operations.
Send only the data required for domain trust verification. Email addresses, message bodies, and user identifiers may contain personal or confidential information, so keep them inside the SIEM unless they are essential to the integration.
Create Analyst-Friendly Alerts
An enriched alert should tell the analyst what happened and why it matters. Include the observed domain, event source, authentication findings, trust result, first-seen time, affected users, and recommended investigation priority. Avoid forcing analysts to open several systems before they can understand the basic risk.
When investigating an unfamiliar sender, domain ownership, DNS configuration, and authentication alignment can provide valuable context. This resource on an unknown sender domain can complement the automated result during manual review.
Add feedback loops to improve the workflow. Track whether analysts confirmed phishing, dismissed the alert, or marked the domain as business-related. Those outcomes can guide allowlists, suppression rules, and future correlation logic without weakening the baseline checks.
Recommended Implementation Practices
- Use a dedicated service account and store credentials in a secrets manager.
- Normalize domains before lookup and cache recent results to control volume.
- Keep “unknown,” “failed,” and “trusted” as separate outcomes.
- Correlate reputation data with DKIM, DMARC, user, URL, and mail-flow signals.
- Log API latency, status codes, lookup timestamps, and enrichment failures.
A small pilot can begin with reported phishing messages or high-confidence email gateway alerts. Measure lookup success, added latency, duplicate volume, analyst decisions, and confirmed incidents before expanding to every inbound message.
Connect the API to a controlled SIEM workflow, validate the enrichment fields against real events, and tune the response rules as evidence accumulates. With the right safeguards, automated domain trust checks become a consistent layer of phishing detection and sender verification rather than another isolated lookup tool.