The short answer: The best MXToolbox alternative depends on the job. For a whole-domain SPF, DKIM, DMARC, MTA-STS, and blacklist check with explanations and no signup, use EmailAudit.io. For DMARC report analysis, look at EasyDMARC or dmarcian. For testing one message's spam score, use Mail-Tester. For SMTP and port diagnostics, MXToolbox is still hard to beat.
This comparison is written by the team behind EmailAudit.io, so treat our own entry with appropriate scepticism. We have tried to be specific about where MXToolbox is stronger, and to avoid stating anything about competitors that we could not verify. Free tiers and limits change often, so check each vendor's site before relying on a limit.
What MXToolbox Does Well
MXToolbox has been the default email diagnostic site for years, and for good reasons:
- Breadth of lookups. The SuperTool covers MX, A, TXT, SPF, DKIM, DMARC, DNS, reverse lookup, blacklist, and SMTP tests from one search box.
- SMTP diagnostics. It can test whether a mail server accepts connections, advertises TLS, and is an open relay. Most domain-security checkers, including ours, do not do this.
- Blacklist depth. It checks a large number of DNS blacklists. Our tool checks 12 zones.
- Monitoring. Paid plans add scheduled monitoring and alerts. Free accounts can set up limited monitoring, with details varying by plan.
- Familiarity. Support staff, hosting providers, and IT consultants all know it, and results are easy to reference in a ticket.
If you are an IT professional diagnosing a delivery failure, a bouncing mail server, or a blocked port, MXToolbox is a good first stop.
Where People Find It Frustrating
The complaints we see repeated are about fit, not accuracy:
- Output is technical. Results show pass, warn, and fail rows with terse text. A business owner who sees "SPF Alignment" has to research what it means.
- No scoring or summary. You run SPF, DKIM, and DMARC as separate lookups, and DKIM requires you to know the selector.
- Monitoring and DMARC reporting need an account. Manual lookups are free. Ongoing monitoring and DMARC report analysis are separate products with their own plans.
- No fix. It tells you the SPF record is invalid. It does not write the corrected one.
None of these makes MXToolbox bad. They make it better for experts than for people checking a domain once.
The Contenders
EmailAudit.io
- Checks: SPF, DKIM (probes 40+ common selectors and detects the provider), DMARC, MTA-STS, and 12 DNS blacklist zones. A combined email security score rates the domain from 0 to 100 with a letter grade.
- Signup: None for the checkers.
- Extras: A PDF audit report via the free email audit, generators for SPF, DMARC, DKIM, and MTA-STS, and optional paid setup services.
- Weaker than MXToolbox: No SMTP or port testing, fewer blacklists, no continuous monitoring product. A DKIM probe can only find selectors on its list, so a custom selector needs to be entered by hand.
EasyDMARC
- Checks: Free DMARC, SPF, and DKIM lookups and a domain scanner, usable without an account according to its site.
- Extras: A DMARC reporting platform with a free plan that has limits on volume and domains. Check current limits.
- Weaker than MXToolbox: Not an SMTP diagnostic tool. Stronger than MXToolbox for report visualisation.
dmarcian
- Checks: Free DMARC, SPF, and DKIM inspection tools and a DMARC record wizard.
- Extras: A reporting product with a free tier at the time of writing, limited in domains and message volume.
- Best for: People who intend to work through aggregate reports and move to enforcement.
Google Admin Toolbox
- Checks: Check MX, Dig, and Messageheader, among other tools. Useful for MX validation and header analysis.
- Limits: It does not give a complete SPF, DKIM, and DMARC audit, and it is built around Google Workspace troubleshooting.
- Best for: Quick MX checks and decoding a delayed message's headers.
Mail-Tester
- How it works: You send a real message to a one-off address, and it scores that message for authentication, content, and blacklist status.
- Limit: The free version allows 3 tests per 24 hours, with extra tests sold separately.
- Best for: Testing one campaign before sending. It does not check a domain without a test message.
Comparison Table
| Tool | Domain-level SPF/DKIM/DMARC | SMTP and port tests | Blacklist check | Signup for lookups | Score or summary | DMARC reports |
|---|---|---|---|---|---|---|
| MXToolbox | Yes, separate lookups | Yes | Yes, large list | No | No overall score | Separate paid product |
| EmailAudit.io | Yes, in one run | No | 12 zones | No | 0-100 plus grade | No (see monitoring tools) |
| EasyDMARC | Yes | No | Not its focus | No for tools | Domain scan | Yes, free plan with limits |
| dmarcian | Yes | No | Not its focus | No for tools | Inspector output | Yes, free tier with limits |
| Google Admin Toolbox | MX and DNS only | MX only | No | None required for core tools | No | No |
| Mail-Tester | Per test message | No | Yes, per message | No | Score out of 10 | No |
"No" in the signup column reflects each vendor's free lookup tools. Account-based features differ. Verify before you rely on it.
Which Tool for Which Problem
| Your situation | Use |
|---|---|
| "Is my domain set up correctly overall?" | Email security score or the free audit |
| "Is this one record valid?" | SPF checker, DKIM checker, DMARC checker |
| "Is my IP or domain blocklisted?" | Blacklist checker, then MXToolbox for a wider sweep |
| "Is my mail server reachable and secure?" | MXToolbox SMTP test |
| "Who is sending as my domain?" | A DMARC reporting service |
| "Why did this specific email go to spam?" | Mail-Tester, then the header analyzer |
| "Do I meet Gmail and Yahoo rules?" | Bulk sender compliance tool |
A reasonable approach is to use two tools. Run a domain-level check, and keep a lookup tool bookmarked for server-level problems.
How to Judge Any Checker
- Does it find the DKIM selector, or make you guess? Selectors are arbitrary, such as
google,selector1,s1, or a vendor-specific string. A tool that lets you enter one but does not probe will return "not found" for a valid setup. See DKIM signature failed. - Does it count SPF DNS lookups? More than 10 breaks SPF. A good checker reports the count and shows the include tree. See SPF too many DNS lookups.
- Does it explain severity? A missing DMARC record and a weak
~allare not the same level of problem. - Is the data live? Tools that cache results can show a fix as still broken.
- Does it tell you what to do next? Even a single sentence helps.
Always cross-check a surprising result with a second tool or a direct DNS query before changing production DNS.
What No Checker Can Tell You
Every tool in this list, ours included, reads public DNS or a single test message. That has limits worth knowing before you trust a green result.
- A valid record is not a working setup. A checker can confirm your SPF syntax is valid and still not know that your invoicing tool sends from an IP that is not in it. Only real mail, or DMARC aggregate reports, reveal that.
- DKIM passing in DNS does not mean signing is on. The public key can sit in DNS while the sending platform has signing switched off. This is the classic Microsoft 365 and Google Workspace gap. Send a message and read the headers to be sure.
- Alignment is invisible to a DNS lookup. DMARC needs SPF or DKIM to pass for a domain that matches the From address. A third-party platform can pass SPF for its own domain and still fail DMARC for yours.
- Results are a snapshot. A new SaaS tool, a registrar change, or an expired DKIM key can alter the picture next week.
- Blacklists differ in impact. Being listed on an obscure list may do nothing, while a listing on a major one can block mail. Read what each list is before panicking. See how to check an email blacklist.
The sensible workflow is a domain check, a test message with the headers inspected, and then DMARC reports over several weeks. A checker covers the first, and the second and third need other tools.
Using Two Tools Together
Different tools are good at different layers, so pairing them is better than picking a winner.
- Start with a whole-domain check to see which of SPF, DKIM, DMARC, MTA-STS, and blacklists need attention.
- Fix what it finds, one record at a time, and recheck each record after the DNS change propagates.
- If mail still bounces, move to server-level diagnostics: reachability, TLS support, reverse DNS. This is where MXToolbox's SMTP tests earn their place.
- If a message lands in spam despite passing everything, test the message itself with the header analyzer or a content scorer.
- Once everything passes, set up reporting so you hear about new problems without having to look.
What to Do After the Check
If the report shows gaps, the order that usually works is: fix SPF, enable DKIM, publish DMARC at p=none, read reports, then enforce. The background is in SPF, DKIM, and DMARC explained, and a blocklisting is covered in how to check an email blacklist. If you want someone to do the work, see email security setup.
Frequently Asked Questions
What is the best free alternative to MXToolbox?
It depends on the task. EmailAudit.io suits one-pass domain checks without signup. EasyDMARC and dmarcian suit DMARC report analysis. Mail-Tester suits per-message testing. For SMTP and port diagnostics, MXToolbox remains a strong option.
Is MXToolbox free?
Its manual lookup tools are free to use. Ongoing monitoring, extended DMARC and deliverability features are separate paid products, so check its pricing page for current plans and limits.
Can I check SPF, DKIM, and DMARC in one place?
Yes. EmailAudit.io checks all three in a single run, along with MTA-STS and blacklists. MXToolbox and others usually run each protocol as a separate lookup.
Why does a checker say my DKIM record is missing when it exists?
Usually because the tool tested a different selector from the one your provider uses. DKIM records live at selector._domainkey.yourdomain.com, so a tool must probe the right selector. Look in a sent message's DKIM-Signature header for s=.
Do I need to monitor DMARC after checking it?
If your policy is p=none, yes. A one-off check shows the record exists, but only aggregate reports show who sends mail as your domain. A DMARC monitoring tool covers that.
Next step: run the free email audit on your domain and compare the result with MXToolbox. The two will agree on the basics, and where they differ, check DNS directly.