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MxToolbox

Diagnose and fix email delivery issues

Deliverability
For AI agents
APICapable readiness
About

What is MxToolbox

MxToolbox runs DNS lookups, blacklist monitoring, SMTP diagnostics, and email header analysis from a single platform, giving teams a clear picture of their sending infrastructure at any point in time. It's built for RevOps teams and GTM engineers at mid-market and enterprise companies who need to diagnose delivery failures, monitor domain health, and stay off blacklists without relying on a dedicated deliverability consultant. The standout capability is DMARC aggregate report analysis — it surfaces authentication failures across sending sources in a way that most DNS tools skip entirely, and pairs with built-in SPF and DMARC record generation to close the loop. Free access covers one monitor and the top 30 blacklists, which is enough for initial audits but falls short for teams managing multiple sending domains at scale. MxToolbox does not function as a sending platform or CRM integration layer — it's a diagnostic and monitoring tool, not an outbound execution engine.

Deliverability
Capabilities

Key features

Deliverability infrastructure

warmup, spam tests, and sender reputation

Outbound webhooks

event-driven integrations

Our verdict

Vanderbuild take

For RevOps and GTM engineers who need to keep sending domains clean and diagnose delivery failures fast, MxToolbox is the most direct diagnostic layer in the deliverability category — it doesn't try to be a sending tool, it just tells you what's broken and why. The REST API is available, so you can wrap MxToolbox lookups into your own automation stack or MCP layer without much friction — agentic readiness is Capable, meaning it's a clean integration target even if there's no native MCP server confirmed yet. Budget for an experienced operator — the free tier is useful for spot checks, but getting full value from DMARC aggregate analysis, inbox placement data, and multi-domain blacklist monitoring requires the $399/month plan and someone who knows how to act on what it surfaces. The honest limitation is that MxToolbox has no native integrations with CRMs or sequencing tools, so any workflow automation connecting diagnostic alerts to your GTM stack will need to be built by your team.

Mateusz Sekta
Founder, vanderbuild
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Our Resources

The wedge

Agentic stack profile

API
REST

Programmatic access available.

REST API — straightforward to call from any agent or workflow tool. Rate limits and auth vary by plan.

API docs →
Agentic readiness
Capable

Solid API access — wraps cleanly for agent use.

Solid REST or SDK access. No MCP server yet, but easy to wrap in custom agent tooling. Most modern SaaS tools land here.

Stack role
Deliverability

Where this tool slots into an agentic pipeline.

Plays the role of Deliverability in an agentic pipeline. Use it to keep email sending reputation healthy — warmup, spam tests.

Compare

MxToolbox alternatives

Tools that solve a similar problem — compared at a glance.

MxToolbox(this tool)
Pricing
Freemium
Budget
$$$
Best for
RevOps, GTM Engineer
Readiness
Capable
API
REST
Mailforge
Pricing
Usage-based
Budget
$
Best for
Founder, GTM Engineer
Readiness
Capable
MCP
No
API
REST
Warmupinbox
Pricing
Custom
Budget
$$$$
Best for
SDR / BDR, RevOps
Readiness
Capable
API
REST
Answers

Frequently asked questions

Does MxToolbox have a public API?

Yes — MxToolbox ships a REST API. Docs: https://mxtoolbox.com/api/api-reference.

How much does MxToolbox cost?

MxToolbox: pricing is freemium, expect higher tier ($$$) spend. Full pricing page: https://mxtoolbox.com/public/planupgrade.aspx.

Who is MxToolbox best for?

MxToolbox is built for RevOps, GTM Engineer. Fits Mid-market (50-500), Enterprise-sized teams.

How well does MxToolbox fit an agentic sales stack?

Tier: Capable. Solid public API, no MCP yet — straightforward to wrap in your own agent tooling.