MXToolbox alternatives: full-stack email deliverability checks

MXToolbox is a free, single-purpose DNS checking tool: it lets you look up MX records, SPF, DKIM, DMARC, and more, one check at a time. That's useful, but it doesn't tell you whether your email will actually land in the inbox. Here's how the alternatives compare.

First, check if you need a full-stack deliverability tool

Most "my email is going to spam" problems are caused by the authentication and reputation layer: a missing or broken SPF, DKIM that isn't signing, a DMARC record set to reject by mistake, no TLS, or a sending IP on a blocklist. You can find and fix all of those for free before spending on placement testing.

Inboxproof runs that full check in about 30 seconds: MX, SPF, DKIM, DMARC, TLS, PTR and IP reputation, with a single spam-risk score and the exact fix for anything failing. No signup. If your domain passes, placement testing is a reasonable next step; if it fails, fix the free stuff first.

Comparison table

How to choose

• Not sure why email is going to spam: start free with Inboxproof. It finds the authentication and reputation problems that cause most spam-folder landings, at no cost.
• Need a quick DNS lookup: MXToolbox is fine for that. It's a single-purpose tool, not a deliverability diagnostic.
• Scaling cold or transactional volume: add an inbox-placement tool (GlockApps, InboxMonster or 250ok) to prove where a real message lands across providers.
• Agency managing many client domains: run free checks per client, then use Inboxproof Pro for continuous monitoring and white-label reports.

The common pattern is to use the free authentication checks first, then placement testing. Skipping straight to a paid placement tool while your SPF or DMARC is broken wastes the test. The email will land in spam for reasons the placement tool can't fix.

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