# Email Deliverability Test

URL: https://iblockspam.com/tools/deliverability-test
Last updated: 2026-10-09

> Send one real email and see what a receiving server sees: SPF, DKIM and DMARC results, the sending server's reverse DNS, blocklists and encryption, and our spam filter's verdict, with fixes.

Free tool: Send one email and see its SPF, DKIM and DMARC results, reverse DNS, blocklists, TLS and spam verdict. Use it at https://iblockspam.com/tools/deliverability-test

## What the Email Deliverability Test checks

Record checkers read your DNS. This test looks at a real message, the way a receiving mail server does, so it catches problems DNS alone can't show: a server that isn't in your SPF record, a service that signs with its own domain instead of yours, or a sending IP with no reverse DNS.

| Area | What we check | Why it matters |
| --- | --- | --- |
| SPF | Result for the envelope sender, and whether that domain matches your From address | Shows whether this server may send for your domain |
| DKIM | Each signature's result, signing domain and selector, and the key we find in DNS | Proves the message wasn't altered and who signed it |
| DMARC | Result, your published policy, and which check gave alignment | Gmail and Yahoo require DMARC for bulk senders |
| Sending server | IP address, reverse DNS (PTR), forward confirmation and public blocklists | Receivers distrust servers with missing PTRs or listings |
| Encryption | The TLS version the server used to reach us | Shows whether mail is encrypted in transit |
| Spam verdict | Whether our spam filter judged the message clean, and its score | A quick signal of how filters see the message |

Each check comes with a plain explanation, and anything that fails links to the tool or guide that fixes it. Checks we couldn't run are marked "not tested", never failed.

## Is this a spam test or an inbox test?

It's a spam test with a real message rather than a guess from DNS. The report shows whether our spam filter judged your email clean or flagged it, and the filter's spam score when it records one (lower is better). It doesn't give a 0-to-10 rating like some mail-tester tools, and no test can promise inbox placement at Gmail, Outlook or Yahoo, because each receiver weighs its own signals. What it does show are the things those receivers check first: authentication, alignment, reverse DNS and blocklists. Fix those, and your mail has a better chance of reaching the inbox instead of the spam folder.

## How to run the test

1. Select **Start a test**. You get a one-time code such as `IBS-7K2Q9XWA`.
2. From the mailbox, server or app you want to test, send any email to **check@iblockspam.com** with the code anywhere in the subject. The page has a button that opens your email app with both filled in.
3. Keep the page open. It checks for your message every few seconds and shows the report when it arrives, usually within a minute.

Test the real path your mail takes. If your website's contact form or your newsletter tool sends mail as your domain, send the test through it: each service has its own SPF and DKIM setup.

## What alignment means

SPF and DKIM can both pass and DMARC can still fail. DMARC asks one more question: did SPF or DKIM pass **for the domain in your From address**? SPF checks the envelope sender (the bounce address), which many services set to their own domain. DKIM checks the `d=` domain in the signature, which some services set to theirs by default. A pass for someone else's domain doesn't count. The report shows which checks were aligned, and our [guide to SPF, DKIM and DMARC](https://iblockspam.com/blog/spf-vs-dkim-vs-dmarc) explains the rules.

## When the message doesn't arrive

Our filter rejects or holds some mail before it reaches the test mailbox, the same as a strict receiver would. If your report doesn't appear within about 10 minutes, that is a result in itself. Look for a bounce in the sending mailbox, check the sending IP with the [Blacklist Checker](https://iblockspam.com/tools/blacklist-checker) and [PTR Lookup](https://iblockspam.com/tools/ptr-lookup), and read [why email lands in spam](https://iblockspam.com/blog/why-did-this-email-land-in-spam). Each code stays open for one hour.

## Privacy

- **Headers only.** We read the message headers to find the code and the authentication results. We never read or store the body or attachments.
- **Deleted immediately.** The message file is deleted as soon as it's read, whether or not it matches a test.
- **One test per code.** Only the first message with a code is used. Any later message with the same code is deleted unread.
- **Reports expire.** A report is visible only to someone with its link, isn't indexed by search engines, and is deleted 24 hours after the test starts.

For your domain's records on their own, use the [Email Health Check](https://iblockspam.com/tools/email-health-check). To build or fix records, use the [SPF Record Generator](https://iblockspam.com/tools/spf-generator) and [DMARC Record Generator](https://iblockspam.com/tools/dmarc-generator).

## Frequently asked questions

### How does the email deliverability test work?

Start a test to get a one-time code, then send any email with that code in the subject to check@iblockspam.com. When it arrives, we read the authentication results our filter recorded, check the sending server and your domain's DNS live, and show a report on the test page, usually within a minute.

### Do you read or keep my email?

We read only the message headers, never the body. The message file is deleted as soon as it's read, whether or not it matches a test. The report keeps the header details it shows, such as your From address and the sending IP, and is deleted 24 hours after you started the test.

### What if my test email never arrives?

If nothing arrives within about 10 minutes, our filter may have rejected the message or held it as spam, which is itself a useful result. Check for a bounce in the sending mailbox, make sure the code is in the subject, and check the sending server with the Blacklist Checker and PTR Lookup.

### Why does SPF pass but DMARC fail?

DMARC needs SPF or DKIM to pass for a domain that matches your From address. Many email services pass SPF for their own bounce domain instead, which doesn't count. Set up DKIM signing for your domain, or a custom return-path domain, so at least one of them is aligned.

### Is this a spam score test?

Partly. It's a spam test with a real message: the report shows whether our spam filter judged it clean or flagged it, plus the filter's own score when it records one (lower is better). It isn't a 0-to-10 rating like some mail-tester tools, and it can't predict inbox placement at Gmail or Outlook, which use their own signals.

### Can I test the same code twice?

No. Each code is used once: we read the first message that carries it and delete any later ones. To test a change, start a new test. You can start up to 10 tests an hour from one connection.

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Source: iBlockSpam, https://iblockspam.com/tools/deliverability-test (this is a Markdown copy; the HTML page is canonical). Quote with attribution and a link. Site index for AI assistants: https://iblockspam.com/llms.txt