MXToolbox

Key points

• Category: Authentication & DNS
• Pricing: Freemium
• Best for: Quick diagnostics during an incident.
• Blocklist checks
• DNS and MX lookups
• Monitoring plans

What MXToolbox is

MxToolbox is a long-standing (20+ years) email delivery diagnostics and monitoring platform best known for its free DNS/MX/blacklist lookup tools, alongside a paid Delivery Center suite for ongoing monitoring. It checks domains and IPs against 100+ blacklists, monitors DNS, mail server and web server health, and provides DMARC/SPF/DKIM setup and management tools including SPF flattening and guided migration to a DMARC reject policy. It reports 42,000+ domains trust the platform and monitors more than 500 DMARC-compliant inbox providers.

IT and email infrastructure teams use MxToolbox for troubleshooting delivery problems (blacklisting events, DNS misconfigurations, mail server outages), tracking recipient complaint feedback loops from major mailbox providers, and testing inbox placement at top providers like Gmail and Outlook.com before a send. Its Adaptive Blacklist Monitoring auto-detects third-party senders (like Mailchimp or HubSpot) sending on a domain's behalf and tracks their reputation alongside the primary domain's own sending IPs.

It sits in the authentication & dns part of an email stack - spf, dkim, dmarc, bimi records and monitoring. In practice it is the right pick when your priority is: quick diagnostics during an incident.

What it does well

The capabilities teams rely on most are blocklist checks, dns and mx lookups, monitoring plans. Taken together these cover the day-to-day work in this category, and they are the features worth testing during a trial rather than reading about.

MxToolbox is widely known and trusted as a free-first diagnostic toolkit (DNS/MX/blacklist lookups) with two decades of history, and its Delivery Center extends that into ongoing adaptive blacklist monitoring across all of a domain's senders, inbox placement testing at major providers, and DMARC/BIMI setup in one dashboard, making it a practical one-stop diagnostic and monitoring tool for email admins.

In real use the strongest points people report are free for ad-hoc checks; covers almost every record type.

Key features

• Blocklist checks
• DNS and MX lookups
• Monitoring plans
• Free for ad-hoc checks
• Covers almost every record type

Pricing tiers

MXToolbox is a freemium product. MxToolbox offers a free tier with one blacklist monitor and access to the top 30 blacklists, and paid Delivery Center plans that unlock more monitors, the full 100+ blacklist set, inbox placement testing, DMARC/SPF/DKIM/BIMI management and recipient complaint monitoring; exact tier prices are not fully published and are best checked on its upgrade/pricing pages, which also offer phone-based sales for larger deployments.

Pricing pages move often, so confirm the current figures with the vendor before you budget. The number worth modelling is not the licence fee on its own but the cost per delivered email once bounces, suppressed contacts and spam-foldered sends are taken out.

Ideal customer profile

• Best fit: Quick diagnostics during an incident.
• Where it sits in the stack: Authentication & DNS - spf, dkim, dmarc, bimi records and monitoring.
• Budget profile: Freemium - suited to teams comfortable with this commercial model.
• Probably not for you if: reports are technical and unformatted would block your team.

What it connects to

MXToolbox is commonly wired into Mailchimp, HubSpot, Marketo, Google Postmaster Tools, Major inbox feedback loop (FBL) providers, DNS record management for major registrars, SIEM/alerting via API and Slack-style notification channels. Check that the specific objects and events you rely on are covered, not just that a logo appears on the integrations page - shallow connectors are a frequent source of rework.

Where it falls short

No tool in this space is complete on its own. With MXToolbox the trade-offs to plan around are reports are technical and unformatted. None of these are reasons to avoid it - they are the gaps another layer of your stack needs to fill.

Much of the depth (inbox placement, adaptive blacklist monitoring, DMARC management) sits behind paid plans whose pricing is not transparently listed, requiring sales contact for larger needs, and it is a diagnostics/monitoring tool rather than a list-verification or DMARC-enforcement automation platform, so it doesn't clean lists or automate SPF record changes the way some competitors do.

A useful test before committing: send a real campaign through your intended setup, then check where it actually lands across Gmail, Outlook, Yahoo and your customers' corporate filters. Tooling that looks identical on a feature list often behaves very differently once reputation and authentication are involved.

The essentials

Category

Authentication & DNS

Pricing model

Freemium

Vendor

mxtoolbox.com

G2 rating

4.5 / 5

Best for

Quick diagnostics during an incident.

Works alongside Warmy

Yes - warm-up, placement, DMARC

Review scores are rounded public averages and change over time - treat them as indicative rather than exact.

How it fits a deliverability stack

Deliverability is decided by four things: the reputation of the sending domain and mailbox, the quality of the list, correct SPF, DKIM and DMARC authentication, and proof of where mail actually lands. MXToolbox covers part of that picture. The mistake most teams make is buying four separate products for those four jobs and still having no single place that tells them whether the last campaign reached the inbox.

Warmy runs warm-up, inbox placement testing, email verification and DMARC monitoring as one platform, which is why MXToolbox usually sits alongside it rather than against it: it keeps doing what it is good at, while reputation, placement and authentication are handled in one loop.

MxToolbox is squarely a deliverability and reputation monitoring tool: it checks blacklist status, DNS/mail server health, DMARC/SPF/DKIM configuration, complaint feedback loops and inbox placement at top providers. It does not verify or clean recipient email address lists, so it should be paired with a verification service for full list hygiene alongside its monitoring and diagnostic capabilities.