Tool
Generate a test inbox, send the exact email from your app or ESP, and get a practical fix order across authentication, DNS, headers, content, links, and infrastructure.
70+
message checks
0-100
report score
API
automation ready
Template previews and copied HTML do not show the final sender path. A useful deliverability test uses the same app, ESP, From domain, Return-Path, DKIM selector, tracking links, and MIME output that users will receive.
Searches such as email deliverability test, email spam checker, and spam test describe the same practical job: send a production-like message, collect receiver-facing evidence, fix the highest-impact problems, and retest.
| Question | Evidence in the report | Next step |
|---|---|---|
| Will authentication pass? | SPF, DKIM, DMARC, alignment, and sender-domain evidence. | Correct DNS or signing configuration before changing content. |
| Does the message look risky? | Headers, MIME structure, SpamAssassin signals, links, and content checks. | Fix the specific finding instead of chasing generic trigger-word lists. |
| What should we verify next? | Prioritized recommendations with a repeatable report. | Retest the same sending path and compare the evidence. |
The report is designed for teams that need to fix and retest, not just admire a number. It connects message evidence to validation, domain monitoring, DMARC, API workflows, and sample reports.
Check signup, reset, billing, invite, newsletter, and campaign templates before users or subscribers see them.
Attach the report to a root-cause workflow so teams can separate authentication failures from content, link, and list risk.
Use API-created tests and report fetching when deliverability QA belongs in CI, release checks, or internal tooling.
Workflow graphic
The strongest spam test does not inspect pasted HTML. It captures the final message after your app, ESP, authentication, tracking links, headers, and footer injection have all touched it.
| Step | What WillItInbox sees | Why it matters |
|---|---|---|
| 1. Generate inbox | A fresh WillItInbox address for this specific test. | Keeps the report tied to one message and one sending path. |
| 2. Send from production-like path | Actual From domain, Return-Path, DKIM selector, MIME, tracking links, and headers. | Catches changes hidden by previews, forwards, or copied HTML. |
| 3. Score evidence | Authentication, DNS, infrastructure, headers, content, links, and hygiene checks. | Shows which findings are receiver gates and which are refinements. |
| 4. Fix and retest | A new report after DNS, template, ESP, or link changes. | Turns a spam score into a repeatable launch QA loop. |
Category matrix
A useful email spam checker should not send teams chasing random trigger-word lists before authentication or routing is fixed. WillItInbox groups findings by the kind of action they need.
| Category | Evidence examples | First action |
|---|---|---|
| Authentication | SPF, DKIM, DMARC, alignment, BIMI, ARC, and sender identity. | Fix before content polish because receivers gate trust here. |
| DNS and infrastructure | PTR, HELO, TLS, MX, blocklist signals, transport policy. | Correct the sending host, DNS, or provider setup. |
| Headers | List-Unsubscribe, Message-ID, MIME, Date, From, and mailer structure. | Make the message machine-readable and bulk-sender compliant. |
| Content and links | Plain text, image ratio, suspicious copy, HTTP links, shorteners, tracking domains. | Fix concrete signals rather than relying on folklore. |
| Reputation context | Domain monitoring, provider dashboards, DMARC reports, and recent incidents. | Use ongoing evidence when a clean message still lands poorly. |
Score interpretation
WillItInbox should win when a team needs to know what to do next. The score summarizes risk, but the sections underneath decide the work.
Broken authentication, malformed DNS, missing sender identity, and rejected infrastructure should block launch.
Missing unsubscribe headers, weak DMARC policy, image-heavy content, or risky links should be fixed before volume.
Reputation, engagement, recipient history, and provider behavior still matter; a technical report is evidence, not a guarantee.
Product proof
The sample report and guide make the product tangible for buyers comparing Mail Tester, spam checkers, and deliverability suites.
Generate a fresh test inbox and send from the same app, ESP, domain, DKIM selector, tracking links, and footer injection you plan to use in production.
See how authentication, DNS, headers, content, links, and infrastructure evidence become a prioritized fix order.
Use docs and API workflows when email checks belong in launch checklists, internal tools, or CI.
Related
Compare one-off scoring with an operational workflow.
See the checks behind the report.
Learn the recommended testing workflow.
Send the exact production-like message and inspect the resulting report.
See how category evidence becomes a prioritized fix plan.
Compare test volume, API access, monitoring, and workspace needs.
Create an account and start running real-message tests.
Read the supporting guide for practical context around email deliverability testing.
Use the REST API reference when validation, bulk jobs, webhooks, reports, or usage need to run from your own systems.
Open the public tool that helps diagnose one part of email deliverability testing.
Read the supporting guide for practical context around email deliverability testing.
Read the supporting guide for practical context around email deliverability testing.
Read the supporting guide for practical context around email deliverability testing.
See how this workflow applies to teams running email deliverability testing.
FAQ
No. It tests technical deliverability evidence and risk signals. Inbox placement also depends on reputation, engagement, recipient history, and provider behavior.
Start with revenue or access-critical mail: signup, password reset, invites, billing, alerts, onboarding, and high-volume campaigns.
No. It tests technical deliverability and spam-risk evidence. Placement also depends on reputation, engagement, recipient history, and mailbox-provider behavior.
Pasted HTML misses ESP rewrites, DKIM signatures, Return-Path, tracking links, headers, MIME boundaries, and sender infrastructure. A real-message test sees the final message.
