Email Diagnostics

Test any sender in under a minute: we give you a one-off address - send an email to it and get a graded report on SPF, DKIM, DMARC, DNS, TLS, blocklists and more. Free, no account needed.

How the email diagnostic works

  1. Step 1

    Start a free test

    We generate a one-off address for you. No sign-up, no software to install.

  2. Step 2

    Send it an email

    From the mail system you want to check, send any message to that address.

  3. Step 3

    Read your graded report

    In seconds you get a Pass / Info / Warning / Critical breakdown of every check.

What the diagnostic checks

Every message is graded against the same checks a strict receiver runs before it decides to accept, junk or reject your mail. See the full breakdown of what each check means.

Authentication

SPF, DKIM, DMARC, From alignment and ARC - proof that you are allowed to send as your domain.

DNS & infrastructure

MX records, reverse DNS (PTR) and the EHLO hostname receivers cross-check before trusting a server.

Transport security

TLS in transit, inbound MX STARTTLS, MTA-STS and TLS-RPT - whether mail travels encrypted.

Reputation & content

DNS blocklists, policy disposition, header hygiene and BIMI - signals filters weigh heavily.

When to use it

  • →Debugging your own sending infrastructure or a new mail server
  • →Vetting a new email provider before you migrate to it
  • →Working out why your mail keeps landing in spam
  • →Confirming SPF, DKIM and DMARC after a DNS change

Frequently asked questions

Is the email diagnostics tool free?
Yes. It is completely free and needs no account - daily limits keep it fast for everyone.
Do I need to install anything?
No. You send an email to the address we give you and read the report in your browser.
Does a passing report mean my mail reaches the inbox?
Not on its own. Authentication and reputation strongly influence placement, but acceptance and inbox placement are separate decisions - see deliverability vs placement.
How long are reports kept?
Test addresses expire after a short while and reports are deleted automatically.
Want to check a single mailbox instead?
Use the send a test email tool to see the real SMTP outcome of delivering to one address.