Defaults.Exposed › Compare › MXToolbox
Defaults.Exposed vs MXToolbox: which domain checker should you use?
Use MXToolbox when you need granular DNS, MX and blacklist diagnostics tool-by-tool. Use Defaults.Exposed when you want a single A–F security grade for your domain across email, TLS, web and DNS, a plain-English fix for each failure, and a percentile showing how you compare to millions of other domains.
Feature comparison
| Feature | Defaults.Exposed | MXToolbox |
|---|---|---|
| Unified A–F grade across all checks | Yes — one grade, email + TLS + web + DNS | No — individual diagnostic lookups |
| Email authentication (SPF / DKIM / DMARC) | Yes | Yes |
| DNS / MX / blacklist diagnostics | Core checks | Extensive — its core strength |
| Web / HTTP security headers | Yes (HSTS, CSP, clickjacking…) | Limited |
| TLS / certificate checks | Yes | Yes |
| Percentile vs a domain population | Yes — "better than X% of .tld" | No |
| Plain-English, per-failure fix guides | Yes, with per-host setup steps | Technical output |
| Result model | Owner-verified self-check (private) | Open public lookups |
| Price for a full check | Free | Free tier + paid monitoring |
Comparison reflects publicly documented features at time of writing; tools change, so check each vendor for the latest. We compare capabilities only and never publish any organisation's per-domain grade.
The short version
MXToolbox is one of the most established names in DNS and email diagnostics. Its SuperTool is superb for ad-hoc lookups — checking MX records, hunting blacklist listings, debugging mail flow. That breadth of diagnostics is its strength, and if that’s what you need, it’s hard to beat.
Defaults.Exposed answers a different question: “how secure is my domain overall, and what do I fix first?” Instead of a wall of individual lookups, you get one A–F grade across email authentication, TLS, web headers and DNS, a percentile against millions of graded domains, and a prioritised, plain-English fix for every failure — with per-host setup steps.
If you live in DNS diagnostics all day, keep MXToolbox in your toolbox. If you want a clear graded posture and a fix list a non-specialist can act on, that’s what we do.
Frequently asked questions
Is Defaults.Exposed a replacement for MXToolbox?
For most owners who just want to know how secure their domain is and what to fix, yes. If you're an IT pro who needs deep, ad-hoc DNS, MX and blacklist diagnostics across many domains, MXToolbox remains excellent at that and the two complement each other well.
Why can't I look up any domain on Defaults.Exposed like I can on MXToolbox?
By design. We only show a domain's full grade to someone who proves they control it, so we never expose another business's posture. MXToolbox's lookups are public, which is great for diagnostics but a different privacy model.
Does MXToolbox give a security grade?
It surfaces detailed pass/fail diagnostics per tool rather than combining everything into one overall letter grade. Defaults.Exposed rolls email, TLS, web and DNS into a single A–F grade plus a percentile.
See your own domain graded A–F across every check in one place — privately, free, owner-only. Run the free check →