Use realistic test results from your mail provider and DNS checks.
Example data table
Sample inputs and outcomes for quick sanity checks.
| Scenario | Auth posture | Lookalike cues | Estimated risk |
|---|---|---|---|
| Established brand domain | SPF pass, DKIM pass, DMARC pass, reject | Similarity 20, no lookalike TLD | Low (≈ 15–30) |
| Newly registered lookalike | SPF unknown, DKIM unknown, DMARC missing | Similarity 92, lookalike TLD yes | High (≈ 80–95) |
| Partial controls | SPF softfail, DKIM pass, DMARC monitor | Similarity 70, incidents 1 | Medium (≈ 45–70) |
Formula used
The calculator builds a weighted risk score from authentication strength, lookalike indicators, transport posture, and incident history. Each factor adds or subtracts points, then the total is clamped to a 0–100 scale.
- Authentication: SPF, DKIM, DMARC status and enforcement.
- Lookalike: similarity score, lookalike TLD, subdomain abuse.
- Posture: MX visibility, transport policies, reporting, branding indicators.
- Message cues: mismatch patterns that often correlate with impersonation.
- Incidents: adds up to 12 points based on recent reports.
How to use this calculator
- Enter the domain you want to evaluate.
- Choose test outcomes for SPF, DKIM, and DMARC from your checks.
- Set DMARC policy and alignment based on your published record.
- Estimate similarity and lookalike cues from observed registrations.
- Click Calculate risk, then export the report as needed.
Security insights
Authentication Signals and Delivery Outcomes
SPF, DKIM, and DMARC are the strongest public indicators of spoof resistance. A pass on all three reduces the chance that receiving systems will accept forged mail. Failures, soft results, or missing records increase attacker flexibility, especially when a domain is frequently targeted. DMARC alignment matters because a message can pass SPF or DKIM while still failing alignment, weakening enforcement at major providers. Treat third‑party senders as part of the same control surface and validate them regularly.
Policy Strength and Organizational Enforcement
DMARC policy expresses how aggressively receivers should handle failing mail. A “none” policy mainly supports monitoring, while “quarantine” and “reject” add meaningful friction for spoofing attempts. Consistent enforcement requires correct alignment, valid reporting addresses, and regular review of aggregate reports. Domains that publish policies but do not act on reports often remain vulnerable to gradual configuration drift. Document ownership, change control, and escalation paths so fixes are not delayed.
Lookalike Exposure and Brand Imitation
Threat actors commonly register lookalike domains using typos, homoglyphs, or alternative top‑level domains. The calculator treats similarity as a measurable exposure factor because user trust can be manipulated before technical checks occur. Subdomain abuse, misleading display names, and shortened links amplify this risk. High‑value brands should prioritize defensive registrations and takedown workflows for close variants. Pair this with user education that highlights subtle spelling changes in real examples.
Mail Infrastructure Posture and Transport Controls
An attacker’s success also depends on how recipients interpret surrounding signals. Visible MX records, clear inbound routing, and stable sending sources simplify trust decisions and improve monitoring. Modern transport policies, such as TLS expectations and reliable DNS, reduce downgrade opportunities. Where possible, publish reporting endpoints and maintain consistent “From” branding to support user recognition and gateway filtering. Logging, rate‑limits, and vendor allowlists help detect abnormal sending patterns early.
Incident Pressure and Continuous Measurement
Recent phishing reports, helpdesk tickets, and user complaints are leading indicators of spoof campaigns. A few incidents can signal wide distribution because many targets never report. Treat the score as a baseline and reassess after DNS changes, new vendors, or mergers that introduce new sending domains. Regular measurement supports targeted remediation, faster response, and measurable risk reduction. Track the score trend over time and link it to concrete work items in your security backlog.
FAQs
What does a high spoof risk score mean?
It indicates weak authentication or enforcement signals, plus brand imitation exposure. Treat it as a prioritization cue to tighten SPF and DKIM, move DMARC toward quarantine or reject, and reduce lookalike registrations through monitoring and takedowns.
Is a DMARC “none” policy always unsafe?
It is useful for visibility, but it does not instruct receivers to block failing mail. Use “none” during rollout, then progress to quarantine or reject once legitimate senders are aligned and reports look clean.
Can SPF alone stop spoofing?
No. SPF checks the sending IP for the envelope domain and can be bypassed with aligned alternate identities. Combine SPF with DKIM signing and DMARC alignment for durable enforcement across major email providers.
How should I estimate lookalike similarity?
Start with common typos, missing characters, swapped letters, and alternate TLDs. Consider homoglyphs that look identical in many fonts. A high similarity percentage and an active lookalike domain both raise impersonation likelihood.
Why do incidents affect the score?
Real reports are evidence of active attacker interest. Even a small number of tickets can represent large campaign volume. Use incidents to trigger deeper investigation, blocklists, user warnings, and accelerated policy hardening.
How often should I recalculate this risk?
Recheck after DNS changes, adding new email vendors, marketing campaigns, or M&A activity. Otherwise, a monthly review keeps drift visible. Track trend lines so improvements and regressions are immediately obvious.