Automating Tickets for Low-Trust Email Domains
A suspicious email does not need to contain malware to create risk. A newly registered sender domain, failed DKIM signature or missing DMARC policy can signal impersonation, invoice fraud or a compromised account. An automated workflow can turn that signal into a ticket before the message reaches the point where someone must investigate it manually.
The basic process is straightforward: inspect the sender domain, assign a trust threshold, enrich the alert with authentication details, and create a case in the service desk platform. Security staff then receive a consistent record instead of relying on inbox rules or someone noticing a warning in Microsoft 365.
This approach suits Australian organisations of all sizes, from a Perth construction business handling supplier invoices to a Sydney technology company with a formal security operations team. It can also support teams working across Australian Eastern, Central and Western time zones, where an overnight alert should be ready for review when staff begin work.
The workflow should be designed around risk rather than a single score. Domain age, reputation, SPF, DKIM, DMARC, message headers and the relationship between the visible sender and return-path address all provide useful context. A low score should trigger investigation, not an automatic accusation.
Define What Counts as Low Trust
Start by establishing a threshold that reflects your environment. For example, a domain trust score below 60 could create a medium-priority ticket, while a failed DMARC alignment check combined with a suspicious display name could create a high-priority case.
Avoid treating every external sender as dangerous. Australian businesses regularly receive legitimate messages from new suppliers, government portals, recruitment platforms and small firms using recently configured domains. Use allowlists for verified partners, but review them regularly so an old exception does not become a permanent blind spot.
Collect the Right Email Signals
Your mail gateway or Microsoft 365 environment should pass the sender domain, envelope-from address, return-path, authentication-results header, originating IP and message timestamp into the workflow. Preserve the original message identifier so analysts can locate the email without forwarding sensitive content unnecessarily.
Check SPF, DKIM and DMARC together. A domain may pass SPF while failing alignment, or it may have a valid DKIM signature from a service unrelated to the address shown to the recipient. The DMARC implementation guide provides useful background for interpreting these controls and deciding which evidence belongs in a ticket.
Connect the Trust Check to Your Tools
Use an API, webhook or low-code connector to submit the sender domain to a reputation service. Trusted Sender Score can support individual checks, bulk assessments and workflow-based verification, allowing the result to be attached to a case automatically.
The automation should record the score, assessment time, domain, authentication results and reason for escalation. Do not store full email bodies by default. A ticket containing excessive personal or commercial information creates avoidable privacy exposure, particularly for organisations handling customer data under the Australian Privacy Act 1988.
Choose the Right Ticket Action
A low-trust result can create a ticket in platforms such as Jira Service Management, ServiceNow or an internal help desk. Set the priority according to the combined risk signals rather than the score alone.
| Signal pattern | Suggested action | Ticket priority |
|---|---|---|
| Low score, valid DMARC, known contact | Monitor and log | Low |
| Low score, new domain, unusual sender name | Ask analyst to review | Medium |
| DMARC failure, lookalike domain, payment request | Quarantine and investigate | High |
| Known malicious indicators or credential link | Block, isolate and escalate | Critical |
Include a clear title such as “Review low-trust sender domain” and add structured fields for the sender, recipient, business unit, score and recommended next step. Structured data makes reporting easier than placing every detail in free-text notes.
Add Deduplication and Escalation
Attackers may send dozens of messages from the same domain, creating a flood of identical cases. Group alerts by sender domain, campaign identifier or message fingerprint within a defined period. A single parent ticket can contain related message IDs and affected mailboxes.
Set escalation rules for cases that remain untouched. A medium-risk alert might go to the security queue after 30 minutes, while a high-risk payment request could notify the incident manager immediately. This is useful for distributed teams in Brisbane, Adelaide and Darwin, where local working hours may differ.
Handle Forwarding and Legitimate Services
Forwarding services can distort authentication results. Newsletters, ticketing systems and cloud email security products may cause a message to appear to originate from an unexpected infrastructure provider. Before blocking a domain, review the forwarded email checklist when DMARC reports show a high proportion of forwarded messages.
Your workflow should distinguish between a direct sender and a message relayed through a trusted platform. Record the intermediate service, ARC headers where available, and whether the recipient expected the forwarding arrangement. This prevents useful business correspondence from being treated as a phishing event.
Test, Measure and Refine the Workflow
Run the process in audit mode first. Generate sample messages from trusted domains, newly registered test domains and known authentication failures. Confirm that the ticket contains accurate evidence, that the correct queue receives it, and that a failed API request does not silently discard the alert.
Track false-positive rates, time to triage, repeated domains, resolved tickets and cases that led to blocking or password resets. Australian organisations covered by the Spam Act 2003 should also ensure that automated responses do not become unsolicited marketing or reveal unnecessary recipient information.
Review thresholds at least quarterly and after major changes to suppliers, email platforms or business systems. A well-tuned workflow gives analysts a prioritised queue, preserves an audit trail and makes low-trust email easier to manage without turning every unfamiliar sender into an emergency.