AI Summary
Are your emails reaching the inbox, or quietly landing in spam? An email deliverability test tells you before customers notice missing receipts.
WP Mail SMTP’s Email Test already confirms your mailer accepts messages. But it can’t tell you whether Gmail or Outlook filed them under spam.
In this guide, I’ll walk you through a free email deliverability test, right from WordPress.
Understanding Email Deliverability Testing
Email deliverability testing measures whether your emails reach the inbox instead of the spam folder or a block. It checks 3 things: your authentication, your content, and your sender reputation.
Those 3 areas map to the 3 test types you’ll use:
- Authentication testing: Confirms SPF, DKIM, and DMARC are set up right.
- Content testing: Scans your message for spam triggers.
- Seed or inbox placement testing: Sends to real addresses to see where mail lands.
When to Run a Deliverability Test
Test your deliverability before any big send and any time your numbers drop. Catching problems early costs far less than repairing a damaged sender reputation.
Run a test in these situations:
- Before launching a new email campaign or sequence
- After changing DNS records, hosts, or email providers
- When open rates or reply rates fall suddenly
- After setting up a new WordPress site that sends email
- After switching mailers in WP Mail SMTP
How to Run an Email Deliverability Test in WordPress
To test email deliverability, send a real email from your site to a testing tool. Then read the report it returns. In WordPress, you can start the test from your dashboard. The full report arrives by email.
Here’s the full process.
What you’ll need (prerequisites)
Before you start, get these ready:
- A sending domain you control (not a free Gmail or Yahoo address)
- Access to your DNS settings, for fixing authentication
- WP Mail SMTP 4.10 or later, with your primary connection fully set up
- An inbox where you can receive the report
Step 1: Send a test email from WordPress
Start by confirming your site can send email at all. WP Mail SMTP includes a built-in email test for this.
- In WordPress, go to WP Mail SMTP » Tools » Email Test.
- Enter an address you can check, then click Send Email.
- Confirm the test email arrives, and note which folder it lands in.
For most mailers, the Email Test also flags DNS record problems with steps to fix. A clean pass just shows a success message.
This test only proves your mailer accepted the message. Where it lands is what the next step checks.
Step 2: Run an email deliverability test with Email Detective
Email Detective is a free deliverability tool from SendLayer, built into WP Mail SMTP. It’s available in both the free and Pro versions of the plugin.
Your site sends a real test email through your primary connection. Email Detective then checks what decides where that email lands.
To use this tool, go to WP Mail SMTP » Tools and click the Email Detective tab.
In the Send a Test Email box, enter the address where you want your report. WP Mail SMTP fills in your own email by default, but you can change it.
Then click Run a Deliverability Test.
Submitting the form emails your report to that address. Email Detective may also send occasional deliverability tips, and you can unsubscribe anytime.
While it works, you’ll see Email Detective Is on the Case… This usually takes less than a minute.
When it’s done, you’ll see Check Your Inbox! Open the report email and click the link inside to see your results.
If the report email doesn’t show up, check your spam folder first. Then click Resend the Report Email.
One thing to know: the report lives on SendLayer’s site. WP Mail SMTP doesn’t display it inside your WordPress admin.
Keep in mind that the test sends 1 real email through your mailer. It counts toward your provider’s sending limits.
Testing a sender outside WordPress, like a help desk? Use the standalone Email Detective site. It gives you a one-time address to send to, and doesn’t require you to sign up for an account
Step 3: Read your deliverability report
Your report opens with an overall deliverability score. Below it, you’ll see a list of what to fix, ordered by severity.
Each item explains the problem and links to a guide on fixing it. For example, a missing DKIM signature shows as Critical. A missing DMARC record or a borderline spam score shows as Medium.
Here’s what each part of the report checks:
| Report section | What it checks | What a failure usually means |
|---|---|---|
| Authentication | SPF, DKIM, and DMARC results on the message that arrived | A DNS record is missing or doesn’t match your mailer |
| Blocklists | Your sending IP and domain against public block lists | Your server or domain has a poor sending history |
| Spam filtering | Your SpamAssassin score and the rules that fired | Content or formatting looks like spam to filters |
| Content analysis | A written review of the tested message’s subject line and wording | Specific phrases or structure to rewrite |
The full report also shows a message summary: subject, HELO name, and sending IP. That’s handy when you’re not sure which server actually sent the email.
Start with anything marked Critical. Those are the issues most likely to push you into spam.
Step 4: Run an inbox placement test
Email Detective tells you why an email might land in spam. An inbox placement test (or seed test) shows where it lands at each provider.
Tools like GlockApps give you seed addresses at Gmail, Outlook, Yahoo, and others. After you send, they report inbox, spam, and block rates per provider.
This matters because providers don’t agree. Your email can reach Gmail’s inbox and still land in Outlook’s junk folder.
Most WordPress sites don’t need this every month. Run it before a big campaign or when one provider’s users keep reporting missing emails.
Step 5: Fix issues and re-test
Fix the weakest area first, then run Email Detective again. To start over, click Start a New Report on the Email Detective tab.
Re-run the test after each fix. Deliverability improves in steps, not all at once.
Fix one thing at a time so you can see exactly what helped.
Troubleshooting Failed Deliverability Tests
To fix a failed test, start with authentication. Add any missing SPF, DKIM, or DMARC records. Then clear blocklists and lower your spam score.
Find the cause that matches your report below.
SPF or DKIM fails
Usually, your mailer’s DNS records aren’t in place. Or your From Email uses a different domain. Add the SPF and DKIM records your mailer gives you, then re-test.
Our guide to adding DNS records shows where to find them for each mailer. Got more than one SPF record? See how to fix multiple SPF records.
DMARC is missing
A missing DMARC record shows as a medium issue, but don’t skip it. Since February 2024, Google requires DMARC from anyone sending 5,000+ emails a day to Gmail (Google’s sender guidelines).
Follow our guide to creating a DMARC record. Start with a p=none policy, then tighten it once your reports look clean.
Your IP or domain is on a blocklist
Your web host’s default mail shares its servers with other sites. One bad neighbor can get the whole server listed.
Connect a dedicated email provider in WP Mail SMTP to move off those shared servers. Then check whether your domain is blacklisted. Request removal from any list that still shows it.
Your spam score is high
Look at the SpamAssassin rules that fired. Each one names a specific trigger, like missing headers or too many links.
Cut heavy images, broken links, and shouty subject lines in your real emails.
The in-plugin test always sends the same sample message, so it can’t show content changes. To re-check, send a real email to the one-time address on the standalone Email Detective site.
Your site couldn’t send the test email
If your mailer returns an error, Email Detective shows that error instead of a report. Your site isn’t sending email at all, so fix your mailer first.
On shared hosting, the host can block or throttle outgoing mail. Connecting a dedicated email provider in WP Mail SMTP routes around it.
Click Read the mailer setup guide, fix the connection, then click Retry Test Email. The WP Mail SMTP troubleshooting guide covers the most common mailer errors.
Email Detective couldn’t confirm delivery
Your site sent the email, but Email Detective never received it. That usually means a receiving server rejected or filtered it.
Click View the Report Page to see the verdict and what to try next.
Email Deliverability Testing Tools Compared
The best free testing tools are Email Detective, mail-tester, MXToolbox, GlockApps, and Google Postmaster Tools. Each covers a different part of deliverability. Most senders use 2 or 3 together.
| Tool | Best for | Free option? |
|---|---|---|
| Email Detective (in WP Mail SMTP) | Auth, blocklist, and spam score check from WordPress | Yes |
| mail-tester.com | Quick spam score from any sender | Yes (limited) |
| MXToolbox | DNS record and blacklist lookups | Yes |
| GlockApps | Inbox placement across providers | Yes (2 free tests) |
| Google Postmaster Tools | Ongoing Gmail spam rate monitoring | Yes |
For hands-on reviews of more options, see our roundup of the best email testing tools.
Common Testing Mistakes to Avoid
A test only helps if you read it right and act on it. Watch out for these:
- Testing once and stopping: Reputation changes over time, so 1 good score isn’t permanent.
- Only testing the sample email: The in-plugin test sends a standard message. Send your real receipts to the standalone Email Detective address too.
- Ignoring Medium items: A missing DMARC record won’t break today’s mail, but it can hurt later.
- Fixing everything at once: Change one thing per test so you know what worked.
- Trusting one provider: Passing at Gmail doesn’t mean you pass at Outlook.
Frequently Asked Questions
Here are answers to the most common questions about testing email deliverability.
What is a good email deliverability score?
It depends on the tool, since each one uses its own scale. On mail-tester, the goal is a perfect 10 out of 10. In an Email Detective report, aim for 0 Critical items.
How do I test if my emails are going to spam?
Send a test email to Email Detective or mail-tester, then read the report. For a per-provider view, email your own Gmail, Outlook, and Yahoo accounts. Check which folder each lands in.
How often should I test email deliverability?
Test once a month as a routine, and always before a major campaign. Also test right after any DNS change or after switching email providers, since those often break authentication.
Why are my WordPress emails going to spam?
WordPress emails usually land in spam because of missing authentication or unreliable default mail. Routing your site through an SMTP provider with valid SPF and DKIM fixes most cases.
What’s the difference between email delivery and deliverability?
Delivery means the receiving server accepted your email. Deliverability means it reached the inbox. You can have high delivery and poor deliverability if your messages land in spam.
Can my emails go to spam even if SPF, DKIM, and DMARC pass?
Yes. Authentication proves who sent the email, not that recipients want it. Spammy content, a blocklisted IP, or high complaint rates can still send it to spam.
Does Email Detective count toward my sending limits?
Yes. Each test sends 1 real email through your primary connection. It counts like any other email you send.
Next, keep an eye on your sending reputation
A deliverability test is a snapshot. Your reputation shifts over time, so checking once isn’t enough.
Read our guide to monitoring your email sending reputation to catch problems before they cost you. For the full Email Detective walkthrough, see the Email Detective doc.
Ready to fix your emails? Get started today with the best WordPress SMTP plugin. If you don’t have the time to fix your emails, you can get full White Glove Setup assistance as an extra purchase, and there’s a 14-day money-back guarantee for all paid plans.
If this article helped you out, please follow us on Facebook and Twitter for more WordPress tips and tutorials.
