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Email deliverability test

Send one email to a test address and see, a few seconds later, whether SPF, DKIM and DMARC pass, whether your server is on a blocklist, how a spam filter scores the message, and the exact fix for every problem.

  • SPF, DKIM, DMARC and ARC
  • Blocklists and reverse DNS
  • Spam score, rule by rule
  • Gmail and Yahoo requirements

1. Send one email to this address

Getting your address

2. Wait here for the report

The report opens here by itself, a few seconds after your email arrives.

Send it the way your real mail goes out: from your app, your provider or your mail client. One message per address, up to 1 MB. Nothing is stored except the report, which is deleted after 7 days.

What a report looks like.

A score out of 10, a short summary of what to fix first, and every check below it with its explanation and fix. Each report has its own link to share with whoever runs your DNS.

A deliverability report scoring 6.9 out of 10: SPF soft fails, List-Unsubscribe lacks one click unsubscribe, and a link uses a shortener, with DKIM, DMARC, reverse DNS and TLS passing.
A real report from this test, for a newsletter sent from the demo domain acme.example: DKIM signed, but its SPF record lists only its email provider and its List-Unsubscribe has no one click link.

What the test checks.

The same checks Gmail, Outlook and Yahoo run when your mail arrives, on the message you actually send. Each one gets a pass, a warning or a fail, a plain English explanation and the fix.

  • Authentication

    SPF with the record we found and how many of its 10 DNS lookups it uses, every DKIM signature with its d=, selector and key size, DMARC with the policy and whether SPF or DKIM align with your From domain, and ARC when a forwarder added it.

  • Sending infrastructure

    Whether the sending IP has reverse DNS that points back to it, whether the server introduced itself with a real host name, and whether it used TLS.

  • Blocklists

    The sending IP and your domains against public DNS blocklists, through our own resolver. A listing comes with the cause to look for and the removal page.

  • Spam score

    The score from rspamd, an open source spam filter, with every rule that fired explained in plain English, so you know which line of the message to change.

  • Gmail and Yahoo rules

    The bulk sender requirements: SPF and DKIM, a DMARC record, an aligned From domain, and List-Unsubscribe with one click unsubscribe, signed by DKIM.

  • Content

    Required headers, a plain text part, the balance of images and text, link domains, shorteners, size against Gmail's clipping limit, and broken HTML.

How to test email deliverability.

Two minutes, from the place your mail really comes from.

  1. 1

    Copy your test address

    Open the test. It gives you a one time address such as test-k7m3qz2x9abc@check.mailbay.dev that works for an hour.

  2. 2

    Send one real email to it

    Send the email the way your real mail goes out: from your app, your email provider or your mail client. Use a real message, not a blank one.

  3. 3

    Read the report

    Keep the page open. The report appears a few seconds after the email arrives, with a score out of 10 and a pass, warning or fail for every check.

  4. 4

    Fix and test again

    Each problem comes with the exact fix, such as the DNS record to publish. Apply it, get a new address and send again until every check passes.

When a check fails.

Most failures are DNS records. SPF lists the servers allowed to send for your domain, DKIM publishes the key that signs your mail, and DMARC tells receivers what to do when neither lines up with your From address. SPF, DKIM and DMARC explained walks through all three with real records.

Sending from your own domain with Mailbay? The domains guide lists the exact MX, SPF, DKIM and DMARC records to publish and checks them for you. Then send a message here to see the result from a receiver's side.

Questions.

Is the email deliverability test free?
Yes. It is free and needs no account. Each address takes one message within an hour, and each network can create 10 addresses an hour.
How do I check SPF, DKIM and DMARC for my domain?
Send a real email from your domain to the test address. The report shows whether SPF, DKIM and DMARC pass for that message, the records we found in DNS, whether SPF and DKIM align with your From domain, and the exact record to publish when something fails. For how the three fit together, read SPF, DKIM and DMARC explained.
How is the score calculated?
Every message starts at 10. Each check that fails or warns takes off the points shown next to it in the report, and the score never goes below 0. The Gmail and Yahoo section repeats some authentication checks; those are counted once.
Do you keep my email?
No. The message is checked in memory and never stored, forwarded or relayed. We keep only the report: the From address, subject, size, sending IP and the findings. Reports are deleted 7 days after the message arrived, and report pages are hidden from search engines.
Can I test email sent by my app or email provider?
Yes, and that is the most useful test: send to the test address from the same code path your users' mail takes, through your provider's API or SMTP. The report then shows that provider's sending IP, signatures and return path as receivers see them.
Why does a blocklist say not checked?
Some lists only answer resolvers they can attribute, or need a key for commercial use, so we query them only when our setup allows it and say so when it does not. Private and local IP addresses are never listed, so they are not checked.
Does the test favour mail sent with Mailbay?
No. If a message came through Mailbay the report says so, but it is scored exactly like any other message.