Available at https://www.suped.com/tools/email-tester.
Send a real email to Suped's test address. The tester parses the message, pulls live DNS for the sending domains, and runs a full set of authentication, reputation, encryption, and unsubscription checks.
How it works
- Go to the email tester page
- Copy the unique test email address shown on the page
- Send an email to that address from the system you want to test
- Suped analyzes the email and shows the results in real time - no page refresh needed
What's tested
The report is split into accordion sections. Each section has its own pass/fail subscore, and the top of the page shows a total tests passed score across every section.
DMARC
- DMARC record found
- Single record (no duplicates)
- Record valid
- Secure policy (quarantine or reject)
- Secure subdomain policy
- DMARC report monitoring configured
- External reporting authorized
- DMARC passed on this email
SPF
- SPF record found
- Single record
- Record valid
- Under 10 DNS lookup limit
- Under 2 void lookup limit
- No include loops
- Under 450 byte limit
- Ends with ~all or -all
- No +all
- No deprecated ptr mechanism
- No duplicate includes
- No empty includes
- No macros
- At least 1 IP or include
- SPF passed on this email
- SPF aligned with the From domain
DKIM (per signature)
Every DKIM-Signature on the email is checked independently. Scores are aggregated across signatures.
- DKIM record found
- Single record
- Record valid
- Supported encryption algorithm (RSA)
- Secure hash algorithm (SHA-256)
- Secure key length (2048-bit)
- Not in testing mode
- DKIM signature passed
- DKIM signature aligned with the From domain
Blocklists
Each identity on the message is checked against 100+ blocklists (DNSBLs).
- Sending IP not on any blocklists
- Visible From domain not on any blocklists
- Return path domain not on any blocklists
- HELO domain not on any blocklists
Reverse DNS
- PTR record configured for the sending IP
- HELO/EHLO hostname matches the PTR hostname
Encryption
- TLS encryption used for delivery
- TLS version secure (TLS 1.2 or TLS 1.3)
Unsubscription
- List-Unsubscribe header present - RFC 2369
- One-click unsubscribe supported - RFC 8058 List-Unsubscribe-Post header, required by Gmail and Yahoo for bulk senders
- Mailto unsubscribe option present - mailto entry in the List-Unsubscribe header
- Visible unsubscribe link in body - a clearly visible unsubscribe link is present in the HTML
Email preview
See how the email renders in HTML, plain text, and raw source. The preview also shows the sending IP, country, sending source (Google Workspace, Microsoft 365, Mailchimp, etc.), and timestamp.
Diagnostics
A Diagnostics section exposes the raw Authentication-Results header, DNS lookups, and DKIM-Signature headers the checker used to generate the report. Useful when debugging a specific failure.
Tests passed score
Every check counts equally towards the tests passed score (e.g. 38 / 42). Each accordion section shows its own subscore so you can see exactly where the failures are.
Shareable results
Every test gets a permanent shareable link via the Share button. Send it to colleagues or clients to show your email authentication status. Viewing a shared link does not require an account.
In-app version and test history
The email tester is also available inside the app under Tools → Email tester. When you are signed in, every test you run is automatically saved to your organization's history. The History button opens a paginated table of every previous test with:
- Sending source, from address, subject, and date
- Per-section pass/fail scores (DMARC, SPF, DKIM, Blocklists, rDNS, Encryption, Unsubscription)
- Total tests passed score
- One-click open to re-view any past test
- Delete action to remove tests you no longer need
History is scoped to your organization, so teammates see the same list. On the public version, clicking History prompts you to sign up - history is only saved once an account exists.
