Official Google, Microsoft, and Azure mailboxes on US IPs, provisioned by API
InboxKit is cold email infrastructure that provisions genuine Google Workspace, Microsoft 365, and Azure tenant mailboxes on US IP space, registers or connects the domains behind them, writes SPF, DKIM, and DMARC automatically, monitors blacklists and inbox placement through an add-on called InfraGuard, and pushes the finished credentials into more than twenty sequencers, priced from about $2.50 per mailbox per month with a full REST API and an MCP server included at every tier.
Overview
InboxKit sits in the layer beneath the sending platform. It does not write sequences, manage replies, or report on campaigns. What it does is the unglamorous work that decides whether any of that lands: buying secondary domains, standing up mailboxes on them, getting the authentication records right, and telling you when one of the accounts starts to rot. Every outbound program eventually has to solve that problem, and most teams solve it badly by hand across a registrar console and a Google admin panel.
The architectural choice that defines InboxKit is that these are real provider accounts. A Google Workspace mailbox bought here is a Google Workspace mailbox, with an admin panel, two-factor authentication, and app passwords, sending from Google's own infrastructure on a US IP. That matters because a meaningful share of B2B recipients sit in enterprise Gmail and Microsoft tenants where provider-to-provider delivery is treated more generously than mail arriving from an unfamiliar SMTP host. It also costs more per mailbox than private SMTP, which is the trade the whole category argues about.
The third option is the interesting one. Alongside per-mailbox Google and Microsoft accounts, InboxKit sells Azure tenants at a flat rate per tenant covering up to a hundred mailboxes, which changes the unit economics completely once you are running at scale: a hundred Microsoft mailboxes under one tenant costs the same as a handful bought individually. Domain isolation panels keep each domain's administration separate so a problem on one does not spread across the estate.
What genuinely distinguishes InboxKit from the rest of this category is that it is built to be operated by software rather than clicked. There is a full REST API with webhooks at every tier, and an MCP server that exposes provisioning, warmup control, health monitoring, placement testing, and sequencer export as tools an AI assistant can call directly. In a category where most vendors still onboard you through a Slack channel and a spreadsheet, being able to ask an agent to buy ten domains, provision thirty mailboxes, start warmup, and push them to Smartlead is a different operating model, not a nicer console.
InboxKit publishes its prices, which is worth stating plainly because several of its competitors do not. Google and Microsoft mailboxes start around $2.50 each per month on annual billing, Azure tenants are a flat $30 a month, warmup is an optional $3 per mailbox, and InfraGuard monitoring is a separate line. The company operates out of Dubai and describes itself as a Google Cloud partner, and it is young, which is the standard caveat across this entire layer.
Best for
Outbound teams and agencies that want genuine Google, Microsoft, or Azure mailboxes rather than private SMTP, published per-mailbox pricing rather than a sales call, and the ability to provision, monitor, and retire infrastructure programmatically from an API, a script, or an AI assistant instead of a support channel.
Not the right fit for
- Anyone looking for a sending platform. InboxKit has no sequences, no unified inbox, and no campaign reporting, so it is always bought alongside a sequencer, never instead of one.
- Teams whose recipients are almost entirely at consumer or small-business domains where cheaper private SMTP mailboxes place about as well, in which case the provider-account premium buys little.
- Buyers who want somebody else to run the whole thing. This is self-serve infrastructure with an API, not the managed, Slack-channel, done-for-you model that ScaledMail and Premium Inboxes sell.
- Very small senders. A few hundred emails a month runs fine from one real mailbox, and a ten-mailbox minimum plan is more infrastructure than the job needs.
- Organizations that require a long public operating history from a vendor before signing, since InboxKit is a young company in a category with high vendor mortality.
How it works
- 1
You choose a mailbox type. Google Workspace and Microsoft 365 mailboxes are priced per mailbox per month; Azure tenants are priced per tenant at a flat rate covering up to a hundred mailboxes, which is the cheapest route to volume if you are willing to run Microsoft infrastructure you administer yourself.
- 2
You bring domains or buy them in the platform. InboxKit registers new domains, connects domains you already own, and connects domains held at Cloudflare directly, so DNS can be written without you exporting and re-importing zone files. There is also a pre-warmed domain inventory for buyers who do not want to wait out an aging period.
- 3
DNS is written for you. SPF, DKIM, and DMARC are configured automatically per domain, along with custom tracking domains, with quoted end-to-end setup around ten minutes and mailboxes typically delivered within thirty to a hundred and twenty minutes of purchase.
- 4
You warm the mailboxes. Warmup is an optional add-on at $3 per mailbox per month, running an isolated pool rather than a shared network, ramping from a couple of emails a day up to about forty as the account establishes a record.
- 5
You turn on monitoring if you want it. InfraGuard checks more than fifty blacklists on a six-hour cycle, watches for DNS records changing or disappearing underneath you, tracks bounce behavior per mailbox, and runs inbox placement tests on a schedule so a deliverability problem arrives as an alert rather than as a quiet collapse in replies.
- 6
You export to a sequencer. More than twenty platforms including Instantly, Smartlead, Apollo, Reply, Lemlist, and PlusVibe accept a direct push, and universal app passwords cover anything that speaks IMAP and SMTP. The same operations are available through the REST API, the webhooks, and the MCP server.
Feature breakdown
30 features in 5 modulesMailbox provisioning
Real provider accounts in three flavors, with Azure tenants changing the unit economics at volume.- Official Google Workspace mailboxes
- Genuine Workspace accounts on US IP space with their own admin panel, not SMTP relays dressed up as Google. Priced from about $2.50 per mailbox per month on annual billing.
- Official Microsoft 365 mailboxes
- The Microsoft side of the same architecture, which matters when a large share of your prospect base sits in Outlook tenants and provider-to-provider delivery works in your favor.
- Azure tenants at a flat rate
- A tenant costs about $30 a month and covers up to a hundred mailboxes, which collapses the per-mailbox cost at scale to a few cents in exchange for administering the tenant yourself.
- Domain isolation panels
- Each domain gets its own separated administration rather than everything living in one console, so a reputation or suspension problem on one domain is contained instead of contagious.
- Mailbox delivery in thirty to a hundred and twenty minutes
- Purchased mailboxes are typically live within two hours, against days of waiting when infrastructure is assembled by hand or bought through a managed provider.
- Bulk operations
- Mailboxes are created, tagged, updated, forwarded, signed, and cancelled in bulk rather than one at a time, which is the difference between managing thirty and managing three hundred.
- Admin panel access with two-factor authentication and app passwords
- You get the real provider console rather than a wrapper, so you can inspect and administer the account, and app passwords give sequencers credentials without exposing the primary login.
Domains, DNS, and authentication
Buy, connect, or import domains, with the records written automatically.- Automated SPF, DKIM, and DMARC
- The three records are written per domain on provisioning. Getting them wrong fails silently, which is why this automation, not the mailbox itself, is the main labor saving in this category.
- Domain registration in the platform
- Search and register secondary domains without a separate registrar account, so the domain, the DNS, and the mailboxes are provisioned in one flow.
- Cloudflare domain connection
- Domains already held at Cloudflare connect directly and have their records managed in place, which is unusual in this category and saves migrating DNS you have deliberately centralized.
- Pre-warmed domain inventory
- A searchable inventory of domains that have already been aged and warmed, for buyers who need to start sending now rather than in three weeks.
- Custom tracking domains
- Link and open tracking runs on a domain that is not your primary one, keeping your real site out of the URL patterns filters cluster on.
- Bulk DNS record management
- Records are listed and edited across the whole estate rather than domain by domain, which is what makes a fifty-domain pool maintainable.
InfraGuard monitoring
The reputation early-warning system, sold as an add-on.- Blacklist monitoring across fifty-plus providers
- Checks run on roughly a six-hour cycle, so a listing surfaces the same day rather than after a week of degraded delivery nobody could explain.
- DNS watchdog
- Alerts when authentication records change or disappear, which happens more often than people expect when domains are shared between marketing, IT, and an outbound team.
- Bounce tracking and high-bounce mailbox reports
- Per-mailbox bounce behavior is tracked and the worst offenders are surfaced as a list, which is how you decide what to pause before it damages the pool.
- Inbox placement tests
- Seed-based placement measurement priced per test, run on demand or on a schedule, turning deliverability from an inference into a reading.
- Scheduled tests and alerting
- Tests can be set to run automatically with alerts and action items attached, so the monitoring keeps working when nobody is watching the dashboard.
- Mailbox health and insights
- Per-mailbox health scoring across the estate, which is the input to the only decision that matters at scale: what to retire and what to replace it with.
Automation and integration
An API, webhooks, and an MCP server, at every tier rather than gated to enterprise.- Full REST API with webhooks
- Domains, mailboxes, warmup, monitoring, and exports are all programmable, and webhooks push state changes out, so provisioning can be part of a client onboarding script rather than a manual task.
- MCP server
- A Model Context Protocol server exposes the platform to AI assistants as callable tools covering workspaces, domains, mailboxes, warmup, InfraGuard, placement tests, and sequencer export. Very little else in this category is agent-operable at all.
- More than twenty sequencer integrations
- Direct push to Instantly, Smartlead, Apollo, Reply, Lemlist, PlusVibe, and others, with export status tracked so you know what actually landed in the sending tool.
- Universal app passwords
- Anything that speaks IMAP and SMTP connects with generated app passwords, which covers every sequencer without a native integration.
- Workspaces and unlimited team members
- Multiple workspaces separate clients or business units, and seats are not metered, so an agency does not pay per person to look at its own infrastructure.
- Tags across domains and mailboxes
- A tagging layer for organizing an estate by client, campaign, or cohort, which is how bulk actions stay safe once the mailbox count is in the hundreds.
Warmup and commercial terms
Warmup is optional and isolated; pricing is published and wallet-based.- Isolated warmup pool
- Warmup runs at $3 per mailbox per month against an isolated pool rather than a giant shared network, ramping from about two emails a day to about forty as the account establishes a record.
- Wallet-based, pay-as-you-go billing
- Spend is drawn against a balance rather than locked into a rigid seat count, so an estate can grow and shrink without a plan change every month.
- Published per-mailbox pricing
- Monthly rates of about $3.50, $3.25, and $2.99 by volume tier, falling to about $3.10, $2.70, and $2.50 on annual billing. Several competitors in this category quote only after a sales call.
- Ninety-five percent inbox placement guarantee
- A published placement claim rather than a vague deliverability promise. Treat it as a commitment to infrastructure quality, not to your campaign results, since list and copy remain yours.
- Twenty-four seven support with enterprise Slack
- Chat, email, and phone support at all tiers, with a dedicated Slack channel and a success manager at the enterprise end.
Use cases
4 documentedAgency onboarding a new outbound client
Every new client needs domains, mailboxes, DNS, warmup, and a push into whichever sequencer that client already pays for, and doing it by hand takes an operator most of a day.
A provisioning script or an assistant calls the API, buys the domains, creates the mailboxes, starts warmup, and exports to the client's sequencer, with the whole estate tagged by client for later bulk actions.
Outbound team selling into enterprise Microsoft tenants
Cheap private SMTP mailboxes were placing poorly against corporate Outlook recipients and nobody could prove why.
Genuine Microsoft 365 mailboxes on US IPs replace the SMTP pool, and scheduled placement tests give a measured before-and-after rather than an argument about vibes.
Operator scaling past a hundred mailboxes
Per-mailbox pricing on real provider accounts starts to dominate the budget once the estate crosses three figures.
Azure tenants at a flat monthly rate for up to a hundred mailboxes each cut the marginal cost of scale dramatically, in exchange for administering the tenants directly.
Team that keeps getting blindsided by deliverability collapses
Reply rates fall, and by the time anybody investigates the domain has been blacklisted for two weeks and half the mailboxes are damaged.
InfraGuard checks blacklists every six hours, watches the DNS records, tracks bounces per mailbox, and runs scheduled placement tests, so the failure arrives as an alert with an action item attached.
Pricing
from About $2.50 per mailbox per month on annual billingPay-as-you-go against a wallet balance, priced per mailbox per month for Google and Microsoft accounts and per tenant for Azure, with warmup and InfraGuard monitoring as separate add-ons and domains billed separately.
| Plan | Price | Includes |
|---|---|---|
| Professional | $39 per month for 10 mailboxes, about $31 on annual billing |
The entry point, aimed at a single team running its own outbound rather than an agency estate. |
| Agency | $99 per month for 30 mailboxes |
Where the multi-client tooling starts to matter more than the unit price. |
| Enterprise | $299 per month for 100 mailboxes |
|
| Azure tenant | $30 per tenant per month, up to 100 mailboxes |
The pricing lever most buyers miss, and the reason to model your estate before comparing sticker prices. |
| Add-ons | $3 per mailbox per month for warmup |
|
Add-ons
- Email warmup ($3 per mailbox per month): Isolated pool rather than a shared warmup network.
- InfraGuard monitoring (Billed separately): Blacklist checks every six hours, DNS watchdog, bounce tracking, placement tests. First month free.
- Inbox placement tests (Priced per test): Run on demand or on a schedule with alerts attached.
Billing notes
- Annual billing cuts roughly ten to fifteen percent off the monthly per-mailbox rate at every tier, which is the largest single discount available.
- Warmup is not included in the mailbox price, so a realistic per-mailbox figure is closer to $5.50 to $6.50 a month once warmup is on, unless your sequencer supplies warmup instead.
- Domains are a separate cost from mailboxes, as they are everywhere in this category, so budget for a pool of secondary domains rather than one.
- The Azure tenant option changes the arithmetic completely at volume and should be modelled before comparing per-mailbox prices with other vendors.
- There is no free trial, which is normal here because every mailbox carries real provider cost from the moment it exists.
- Billing runs against a wallet balance rather than a fixed subscription, so scaling an estate up or down does not require a plan change.
Value assessment: On published prices InboxKit is the cheapest genuine provider-account mailbox in this category, undercutting Primeforge at $4.50 a slot and Premium Inboxes at $3.50, and sitting far below buying Google Workspace or Microsoft 365 seats directly at $6 to $7 each. It is not the cheapest mailbox available, because private SMTP vendors like Maildoso go under a dollar, but that is a different product with lower per-mailbox throughput. The honest comparison at thirty mailboxes is roughly $99 a month here against about $135 at Primeforge and about $105 at Premium Inboxes, before warmup, with the API, the MCP server, and the workspace tooling included rather than gated. Add warmup and InfraGuard and the effective cost roughly doubles, which is the number to use when comparing against vendors that bundle warmup into the sticker price.
Strengths & limitations
Strengths
- Genuine Google Workspace, Microsoft 365, and Azure accounts rather than private SMTP dressed up as provider mailboxes.
- The lowest published price for real provider-account mailboxes in this category, with the rates on the site rather than behind a sales call.
- Azure tenants at a flat monthly rate for up to a hundred mailboxes, which is the cheapest published route to volume anywhere in this layer.
- A full REST API with webhooks at every tier, not gated behind an enterprise plan.
- An MCP server that makes the whole platform operable by an AI assistant, which effectively nothing else in this category offers.
- InfraGuard monitoring covering more than fifty blacklists on a six-hour cycle, DNS drift, bounce behavior, and scheduled placement tests.
- Domain isolation panels and per-domain administration, which contains a suspension or reputation problem instead of letting it spread.
- Cloudflare domain connection and a pre-warmed domain inventory, both of which remove specific waits most competitors leave in place.
Limitations
- Not a sending platform, so it is always a second bill alongside a sequencer.
- Warmup and monitoring are add-ons rather than included, so the headline per-mailbox price is roughly half the real running cost.
- The Azure tenant option is only cheap if you are prepared to administer a Microsoft tenant, which is genuine operational work most small teams underestimate.
- Self-serve by design, so buyers who want a managed service with an operator in a Slack channel are better served elsewhere in this category.
- The company is young and privately held with limited public disclosure, in a category where vendors appear and disappear quickly.
- The ninety-five percent placement guarantee covers infrastructure quality and cannot cover the two things that actually sink most campaigns, which are list quality and copy.
- Corporate details, including founding year and ownership, are thinly documented in public sources compared with the depth of the product documentation.
Head-to-head comparisons
6 alternativesInboxKit vs Primeforge
from $4.50 per mailbox slot per month, ten-slot minimum, so about $45 per monthThe closest like-for-like comparison in this category, since both sell genuine Google and Microsoft mailboxes on US IPs. Primeforge is about $4.50 per slot with a ten-slot minimum and sits inside the Salesforge stack alongside a sequencer, warmup, and an AI SDR. InboxKit is cheaper per mailbox, adds Azure tenants as a flat-rate volume option, and ships a full API and an MCP server rather than assuming you will work in a console. Buy Primeforge if you want the surrounding stack; buy InboxKit if the infrastructure is the product and you intend to automate it.
Full InboxKit vs Primeforge comparisonInboxKit vs Maildoso
from $75 per month for thirty mailboxes, about $2.50 eachAn architecture choice rather than a price comparison. Maildoso runs its own SMTP infrastructure and sells mailboxes from forty-nine cents with published guidance of about fifteen cold sends a day each; InboxKit sells real provider accounts at about $2.50 that sustain roughly double that. At high volume Maildoso is decisively cheaper per send. At any volume where placement into enterprise Gmail and Outlook tenants is the binding constraint, provider accounts are the safer buy, and InboxKit is the cheapest way to get them.
Full InboxKit vs Maildoso comparisonInboxKit vs Zapmail
from $39 per month for ten Google mailboxesBoth sell real Google and Microsoft mailboxes with the DNS done for you, so the split is regional and operational. Zapmail offers EU IP options and pre-warmed mailboxes and leans on speed to first campaign; InboxKit is US-IP focused, adds Azure tenants, InfraGuard monitoring, and an API and MCP server built for programmatic estates. Choose Zapmail for European sending and a fast standing start, InboxKit when you want to run the infrastructure like infrastructure.
Full InboxKit vs Zapmail comparisonInboxKit vs Inframail
from About $129 per month, or near $85 a month billed annuallyTwo different pricing philosophies. Inframail charges a flat monthly fee for unlimited Microsoft inboxes with a dedicated IP attached, which is unbeatable if you genuinely need hundreds of mailboxes on one bill. InboxKit charges per mailbox but offers Google as well as Microsoft, publishes granular pricing, and gives you an API and monitoring stack Inframail does not match. Under about forty mailboxes InboxKit is usually cheaper; well above that, model both carefully.
Full InboxKit vs Inframail comparisonInboxKit vs Premium Inboxes
from About $3.50 per inbox per monthSelf-serve against done-for-you. Premium Inboxes sells human-configured Google mailboxes from $3.50 with unlimited replacements and founder-level support, and no public API. InboxKit is cheaper, covers Microsoft and Azure as well as Google, and is programmable end to end. If you want somebody else to own the setup and you never intend to script it, Premium Inboxes is the calmer purchase; if you want control and automation, InboxKit is the stronger platform.
Full InboxKit vs Premium Inboxes comparisonInboxKit vs Smartlead
from $39/moComplementary rather than competing. Smartlead connects unlimited mailboxes, which turns the only real constraint on a program into how many mailboxes you are willing to buy, and InboxKit is one of the cheapest ways to buy real provider accounts to fill it. The pairing is common: an uncapped sequencer plus programmatically provisioned infrastructure, with placement testing on the infrastructure side catching problems the sequencer will never see.
Full InboxKit vs Smartlead comparisonImplementation & onboarding
- Setup time
- About ten minutes of configuration, with mailboxes typically delivered inside thirty to a hundred and twenty minutes. Real sending volume still waits on warmup, so plan two to three weeks before a new estate is at full capacity.
- Learning curve
- Low for the console, moderate for the judgement. Buying and connecting mailboxes is simple. What takes discipline is holding to a sane number of mailboxes per domain, ramping slowly, and acting on InfraGuard alerts rather than filing them. The Azure tenant option adds real administrative learning if you take it.
- Onboarding
- Entirely self-serve with published prices and no mandatory sales call. Enterprise buyers get a dedicated Slack channel, a success manager, and a white-glove migration service for moving an existing estate across.
- Migration notes
- Domains are the portable asset and mailboxes are not: leaving means repointing DNS and rebuilding accounts elsewhere, which is true of every vendor in this category. Because mailboxes are real provider accounts reachable over IMAP and SMTP with app passwords, changing sequencer never requires changing infrastructure. The white-glove migration service exists specifically for buyers arriving from another provider with an estate already in flight.
Platform, API & security
- Platforms
- Web appREST APIWebhooksMCP serverProvider admin panels for Google, Microsoft, and Azure
- API
- Full REST API with webhooks included at every tier, covering workspaces, domains and DNS, mailbox provisioning, warmup control, monitoring, placement tests, and sequencer export. An MCP server exposes the same surface as callable tools for AI assistants, which is close to unique in this category.
- Compliance
- SPF, DKIM, and DMARC configured automatically on every provisioned domainTwo-factor authentication on provider admin panels, with app passwords used for sequencer credentialsCAN-SPAM and GDPR sender obligations remain entirely the customer's, since InboxKit supplies infrastructure and never touches campaign content
- Data residency
- US IP space is the advertised default for Google and Microsoft mailboxes. Confirm directly if regional hosting is a hard requirement.
- SSO
- Not advertised.
- Security notes
- Mailboxes are genuine provider tenants rather than relays, so account security is Google's or Microsoft's own, with two-factor authentication and app passwords available. Domain isolation panels keep administration separated per domain, which limits the blast radius when one domain is suspended or listed. Custom tracking domains keep the primary web domain out of tracked link patterns.
Support & resources
- Channels
- Twenty-four seven chatEmail supportPhone supportDedicated Slack channel on enterprise plansWhite-glove migration service
- Documentation
- Product documentation plus a substantial published library on infrastructure cost modelling, mailbox limits, domain strategy, and competitor comparisons.
- Community
- No public forum. Third-party review coverage is positive but still thin, which is typical for a vendor of this age.
Company
- Founded
- 2024
- Headquarters
- Dubai, United Arab Emirates
- Ownership
- Privately held
- Employees
- Not disclosed
- Funding
- No outside funding disclosed. The company describes itself as a Google Cloud partner and lists enterprise logos among its customers. Corporate detail beyond that is thin in public sources, which is worth weighing against the depth of its product documentation.
Timeline
- 2024Launches as a cold email infrastructure provider selling official Google Workspace and Microsoft 365 mailboxes on US IPs with automated DNS configuration.
- 2025Adds Azure tenants at a flat monthly rate covering up to a hundred mailboxes, changing the unit economics of scaling an estate.
- 2025Ships InfraGuard, bundling blacklist monitoring across more than fifty providers, a DNS watchdog, bounce tracking, and inbox placement tests.
- 2026Expands to more than twenty direct sequencer integrations, adds Cloudflare domain connection and a pre-warmed domain inventory, and publishes an MCP server so AI assistants can provision and monitor infrastructure directly.
Integrations
- Instantly
- Smartlead
- Apollo
- Reply
- Lemlist
- PlusVibe
- Any IMAP and SMTP sending platform via app passwords
- Cloudflare
- REST API and webhooks
- MCP server
Frequently asked questions
10 questionsWhat is InboxKit and is it a sending platform?
InboxKit is cold email infrastructure, not a sending platform. It provisions Google Workspace, Microsoft 365, and Azure mailboxes, registers or connects the domains behind them, writes SPF, DKIM, and DMARC automatically, and exports the credentials to a sequencer. It has no sequences, no unified inbox, and no campaign reporting, so it is always a second purchase alongside a sending tool such as Smartlead or Instantly.
How much does InboxKit cost per mailbox?
Google and Microsoft mailboxes run about $3.50, $3.25, and $2.99 a month by volume tier, falling to about $3.10, $2.70, and $2.50 on annual billing. Plans start at $39 a month for ten mailboxes, $99 for thirty, and $299 for a hundred. Azure tenants are a flat $30 a month for up to a hundred mailboxes. Warmup adds $3 per mailbox and domains are billed separately.
Are these real Google Workspace and Microsoft 365 accounts?
Yes. They are genuine provider accounts on US IP space with their own admin panels, two-factor authentication, and app passwords, not SMTP relays presented as provider mailboxes. That is the central difference from vendors like Maildoso and Infraforge, which run their own infrastructure, and it is why the per-mailbox price is higher and the per-mailbox sending capacity is greater.
What is InfraGuard?
InfraGuard is InboxKit's monitoring add-on. It checks more than fifty blacklists on roughly a six-hour cycle, watches for DNS records changing or disappearing, tracks bounce behavior per mailbox and surfaces the worst offenders, and runs inbox placement tests on demand or on a schedule with alerts and action items attached. It is billed separately from mailboxes, with the first month free.
Does InboxKit include warmup?
Warmup is an optional add-on at $3 per mailbox per month, running against an isolated pool rather than a shared network and ramping from about two emails a day to about forty. It is not included in the mailbox price, so if your sequencer already supplies warmup you can skip it, and if it does not, budget roughly double the sticker price per mailbox.
Does InboxKit have an API?
Yes, a full REST API with webhooks at every tier rather than gated to enterprise, covering domains, DNS, mailboxes, warmup, monitoring, placement tests, and sequencer export. It also publishes an MCP server, which lets an AI assistant provision domains and mailboxes, start warmup, check health, and push credentials to a sequencer as tool calls. Almost nothing else in this category is agent-operable.
What is the Azure tenant option and should I use it?
An Azure tenant costs a flat $30 a month and covers up to a hundred mailboxes, which is the cheapest published route to volume in this category by a wide margin. The catch is that you administer the tenant yourself, which is real operational work. It suits teams with technical capacity running large estates, and it is the wrong choice for a small team that wants mailboxes to simply appear.
Which sequencers does InboxKit connect to?
More than twenty directly, including Instantly, Smartlead, Apollo, Reply, Lemlist, and PlusVibe, with export status tracked so you can confirm what actually reached the sending tool. Anything without a native integration connects over IMAP and SMTP using generated app passwords, which covers effectively every sequencer on the market.
Is there a free trial?
No. Every mailbox carries real provider cost from the moment it is created, which is why no vendor in this category offers a free trial. Billing runs against a wallet balance rather than a fixed subscription, so the practical way to evaluate is to buy a small number of mailboxes on monthly billing, run placement tests, and scale only if the readings hold.
How does InboxKit compare with buying Google Workspace directly?
Buying seats directly from Google or Microsoft costs roughly $6 to $7 a mailbox a month and leaves you to register the domains, write the DNS records, create the accounts, and monitor them yourself. InboxKit is roughly a third of that price with the provisioning and authentication automated, which is the whole reason this category exists. The tradeoff is that the accounts are supplied through a reseller rather than held in your own billing relationship.
Editorial verdict
InboxKit is the most complete self-serve product in cold email infrastructure right now. It sells the mailbox type most buyers actually want, genuine Google, Microsoft, and Azure accounts, at the lowest published price in the category, and it is the only vendor here built on the assumption that infrastructure should be provisioned by software rather than by a support channel. The API at every tier and the MCP server are not marketing garnish; they change how an agency onboards clients and how an operator manages an estate of hundreds of mailboxes. Two caveats belong in any decision. The headline per-mailbox price roughly doubles once warmup and InfraGuard are on, so compare fully loaded costs against vendors that bundle those in. And the company is young with thin public corporate disclosure, which in a category with this much churn argues for monthly billing and a real placement test before you commit an entire outbound program to it.
Written by the SaaSTracker editorial team. Awards, when shown, are judged against the published criteria in our methodology.
Awards & badges
2 heldInboxKit holds 2 awards from the SaaSTracker editorial program. Badges may be displayed by the vendor; each embed links back to this profile.
Category Leader · Cold Email Infrastructure
“Official Google, Microsoft, and Azure mailboxes at the lowest published price in the category, with automated DNS, InfraGuard monitoring, and more than twenty sequencer integrations behind them.”
<a href="https://saastracker.org/products/inboxkit"><img src="https://saastracker.org/badges/embed/inboxkit/category-leader-summer-2026.svg?v=2" width="180" height="180" alt="InboxKit: Category Leader, Cold Email Infrastructure. SaaSTracker Summer 2026 Awards." /></a>
Ease of Use · Cold Email Infrastructure
“Ten minutes of setup, mailboxes live inside two hours with SPF, DKIM, and DMARC already written, and a one-click push into the sequencer, with no sales call at any tier.”
<a href="https://saastracker.org/products/inboxkit"><img src="https://saastracker.org/badges/embed/inboxkit/ease-of-use-summer-2026.svg?v=2" width="180" height="180" alt="InboxKit: Ease of Use, Cold Email Infrastructure. SaaSTracker Summer 2026 Awards." /></a>