MXToolbox is often the first tool people find when diagnosing email problems. It's been around for years, covers a lot of ground, and shows up at the top of search results for most email diagnostic queries.
But it has limitations that lead a lot of people to look for alternatives. This guide compares five free email security checkers — including what each one checks, whether signup is required, and whether any of them help you fix what they find.
Why People Look for MXToolbox Alternatives
Most people looking for alternatives run into the same friction:
Signup required for full access. MXToolbox's free tier is limited. To get comprehensive DMARC analysis, historical data, or monitoring features, you need to create an account and move to a paid plan.
Pass/fail results with limited context. The output shows whether your records exist and whether they have obvious errors. It doesn't explain what the failure means for your business, how serious it is, or what to do about it.
Diagnostic only. MXToolbox identifies problems. When you find a misconfigured SPF record or a failed DMARC check, you're on your own to fix it.
For IT professionals who know exactly what they're looking at, these limitations are manageable. For business owners, marketing managers, or anyone who didn't grow up configuring DNS records, they're barriers.
What to Look for in an Email Security Checker
Before comparing tools, here's what matters:
- No signup friction — you should be able to run a check without creating an account
- Broad coverage — SPF, DKIM, DMARC, blacklists, and MTA-STS in one place
- Business-context explanations — not just pass/fail, but what the result means
- Remediation path — ideally, a way to fix what's found, not just identify it
The 5 Tools Compared
1. MXToolbox
Free tier: Yes, with limitations
Signup required: Required for full DMARC analysis and monitoring
What it checks: MX records, SPF, DKIM (limited selector probing), DMARC, blacklists, SMTP diagnostics
Remediation offered: No
MXToolbox is the category incumbent. It covers a wide range of DNS and mail diagnostics and is useful for IT professionals who need quick lookups. The free tier is functional for basic checks, but DMARC analysis and monitoring require a paid account. Results are technical and assume familiarity with DNS concepts.
Best for: IT professionals who need quick DNS lookups and are comfortable interpreting raw technical output.
2. DMARC Analyzer (by Mimecast)
Free tier: Trial period
Signup required: Yes
What it checks: DMARC records, aggregate report analysis, sender discovery
Remediation offered: Consultation available
DMARC Analyzer is focused specifically on DMARC — it's strong for aggregate report parsing and sender discovery. The downside is that it requires account creation and is focused on a single protocol. It doesn't check SPF syntax, DKIM, or blacklists.
Best for: Larger organisations that are deep into DMARC implementation and want detailed aggregate report analysis.
3. Mail-Tester
Free tier: Yes (3 free tests per day)
Signup required: No
What it checks: Overall deliverability score — content, authentication, blacklists, formatting
Remediation offered: No
Mail-Tester works differently from the others. You send a test email to a unique address they provide, and it scores your email on deliverability factors. It's useful for checking whether a specific email would pass spam filters. It doesn't do standalone DNS record lookups or domain-level checks without sending an email.
Best for: Email marketers who want to test a specific email campaign before sending.
4. Google Admin Toolbox (Dig / Check MX)
Free tier: Yes
Signup required: Google account
What it checks: MX records, SPF, DNS propagation
Remediation offered: No
Google's Admin Toolbox is a set of diagnostic utilities primarily designed for Google Workspace administrators. The Check MX tool validates MX and SPF records. It's accurate and authoritative but limited in scope — it doesn't check DKIM, DMARC, or blacklists.
Best for: Google Workspace admins troubleshooting MX or SPF configuration issues.
5. EmailAudit.io
Free tier: Yes — all tools completely free
Signup required: No
What it checks: SPF, DKIM (22+ selectors probed with provider auto-detection), DMARC, MTA-STS, blacklists (12 DNSBL zones), full security score
Remediation offered: Yes — fixed-price professional services ($99–$2,500), 24–72hr turnaround
EmailAudit.io runs six diagnostic tools against your domain with no account required. The security score is weighted across all checks and presented as a 0–100 score with an A–F letter grade.
Key differentiators:
- 22+ DKIM selectors probed with automatic provider detection — more comprehensive than single-selector lookups
- 12 DNSBL blacklist zones scanned simultaneously — broader coverage than most free tools
- Business-context results — each finding includes an explanation of what it means and why it matters, not just pass/fail
- Branded PDF audit report — delivered to your inbox, formatted for sharing with clients or stakeholders
- Remediation services attached — when the audit finds problems, there's a fixed-price service to fix them professionally
Best for: SMBs and IT consultants who want comprehensive diagnosis and a clear path to fixing what's found, without creating accounts or interpreting raw DNS output.
Comparison Table
| Tool | Free Tier | Signup Required | Checks SPF/DKIM/DMARC | Checks Blacklists | PDF Report | Remediation |
|---|---|---|---|---|---|---|
| MXToolbox | Limited | Required for full access | Yes | Yes | No | No |
| DMARC Analyzer | Trial only | Yes | DMARC only | No | No | Consultation |
| Mail-Tester | 3/day | No | Via test email | Yes | No | No |
| Google Admin Toolbox | Yes | Google account | SPF/MX only | No | No | No |
| EmailAudit.io | Full access | No | Yes (all three) | Yes (12 zones) | Yes | Yes (fixed-price) |
Which Tool Is Right for You?
If you're an IT professional who needs quick DNS lookups and knows how to interpret the results — MXToolbox works fine for that.
If you're a business owner or manager who wants to understand your email security posture without studying DNS documentation — EmailAudit.io is the better starting point. No account, results in seconds, plain-English explanations, and a PDF you can act on.
If you're an SMB IT consultant who needs a professional report to share with clients — the Full Audit PDF from EmailAudit.io is the only free tool in this list that delivers one.
For a deeper understanding of what these tools are checking, see SPF, DKIM, and DMARC explained and how to check if your domain is on an email blacklist.
Try EmailAudit.io free — no account needed, results in seconds at EmailAudit.io