Compare/Head to head

MxToolbox vs Warmbox

Same facts, side by side: starting price, free tier, MCP, API and what each one is actually built for.

Starting price

MxToolbox

$129/mo Free tier

MxToolbox is the free DNS and blacklist lookup site most email admins already know, with paid Delivery Center plans for DMARC, inbox placement and blacklist monitoring. It suits agencies that want to check a domain setup fast for free and, at scale, monitor every sender on their domains. The free plan covers 1 domain, paid plans start at $129/month, and no free trial is stated.

Where MxToolbox fits

  • Quick free checks of MX, SPF, DKIM and DMARC records
  • Checking whether a sending IP or domain is blacklisted
  • Teams moving a main domain to DMARC reject
  • Agencies monitoring third-party senders on client domains

Warmbox

$15/mo

Warmbox runs automated email warmup to lift sender reputation. The listing floor is $15/mo.

Where Warmbox fits

  • New domains that need a warmup network before cold volume
  • Solo senders who want a dedicated warmup tool under $20/mo
  • Agencies warming many client inboxes on a low per-box bill
  • Teams that already sequence in Instantly and want a second warmup opinion

At a glance

DetailMxToolboxWarmbox
Starting price$129/mo$15/mo
Free tier✓Yes–No
MCP server–No–No
Public API✓Yes–No
Listed underDeliverabilityDeliverability

Where they pull apart

MxToolbox

Stands out: Its free lookups need no account and check a sending IP against 100+ blacklists in seconds, which is quicker than signing up for a testing tool. Adaptive blacklist monitoring watches every third-party service sending as your domain, not only the IPs you list by hand.

Watch out: The jump from free to $129/month is steep, and both paid plans cap you at 5 domains, which a cold email setup with many domains can outgrow. There is no warm-up and inbox placement covers only Google, Yahoo and Outlook.com.

Not the right fit for

  • Cold email setups spread across more than 5 domains
  • Anyone needing mailbox warm-up
  • Small senders who want cheap paid monitoring

Warmbox

Stands out: $15/mo is the cheapest dedicated warmup listing in this set, below Mailreach's $20/mo and well below Folderly's $79/mo monitor.

Watch out: Warmup is not sending. You still need a sequencer. Results take weeks, and a burned domain will not be saved by a $15 plan alone.

Not the right fit for

  • Buyers who want inbox-placement analytics, not a warmup bot
  • Teams that expect warmup to replace authentication and list hygiene

Pros and cons

MxToolbox

  • Free lookups with no account
  • Blacklist check against 100+ lists
  • REST API for lookups and monitors
  • Paid plans start at $129/month
  • 5 domain cap on both paid plans
  • No warm-up or free trial stated

Warmbox

  • Published $15/mo listing, low for a dedicated warmup network
  • Unbundled from any one sequencer
  • Simple job: reputation, not campaigns
  • Does not send campaigns or host mailboxes
  • Overlap with Instantly and Smartlead bundled warmup
  • Will not rescue a domain with a broken DMARC record

What each one costs

MxToolbox

$129/mo

MxToolbox has a Free plan at $0/month with weekly blacklist monitoring of the top 30 lists for 1 domain. Delivery Center costs $129/month for 5 domains and 500,000 messages, with 30 inbox placement tests a month, DMARC reporting, complaint reporting, adaptive blacklist monitoring, mailflow monitoring, BIMI management and onboarding support. Delivery Center Plus costs $399/month and raises inbox placement tests to 100 a month and message volume to 5,000,000, and adds SPF flattening and advanced threat tools. Managed Services is custom priced and adds hands-on SPF, DKIM and DMARC setup and ongoing expert monitoring. The vendor does not state a free trial. Confirm current terms on the vendor site.

Checked 4 Nov 2026

Warmbox

$15/mo

Warmbox lists from $15/mo for automated email warmup. Confirm live per-mailbox versus flat pricing and any volume packs on the vendor pricing page. Confirm current terms on the vendor site.

Checked 4 Nov 2026

Common questions

Is MxToolbox cheaper than Warmbox?
Warmbox starts lower, at $15/mo against $129/mo for MxToolbox. That is the entry plan on each side, so the real number depends on seats and the tier you land on.
Can you try MxToolbox or Warmbox for free?
MxToolbox carries a free tier on our listing.

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Editorial listings, never paid rankings. Prices checked 4 Nov 2026. Confirm current terms on the vendor site. Spot an error?