InboxKit
Cold email infrastructure. US-IP Google Workspace and Microsoft 365 mailboxes with automated DNS; warmup is a paid add-on.
In our stackLast reviewed July 17, 2026
What InboxKit actually is.
InboxKit provisions Google Workspace, Microsoft 365, and Azure mailboxes for cold email sending. Connect a domain and it handles the setup: DNS records (SPF, DKIM, DMARC), an admin panel per domain with two-factor login, and app passwords for whatever sequencer you're using. Team access isn't capped either, so agencies running several client domains aren't paying per seat to manage them.
It doesn't send anything, though. InboxKit stops at the mailbox and the infrastructure around it: sending and sequencing happen in a separate tool that connects to the mailboxes via API, webhook, or app password. Warmup and the blacklist-monitoring add-on (InfraGuard) also sit outside the base plan price, so the number on the pricing page isn't the full cost of a protected setup.
What it does
- Provisions Google Workspace, Microsoft 365, and Azure mailboxes from one dashboard.
- Automates DNS setup: SPF, DKIM, and DMARC records, configured per domain.
- Gives each domain its own admin panel with two-factor login.
- Warmup add-on ramps sending volume from 2 to 40 emails a day.
- InfraGuard add-on tracks blacklist status, bounce rates, and inbox placement.
- Ships pre-built connectors for tools like SmartLead, Instantly, Apollo, and Reply.
- Full REST API with webhooks for custom integrations.
Where it sits in the pipeline.
- AI & Intelligence
- Data & Enrichment
- Scraping & Custom Data
- Email Infrastructure & Deliverability
- Outreach & Sending
- LinkedIn & Multichannel
- Signals & Intent
- Calls & Meetings
- CRM & Pipeline Ops
Runs well with
The tools we'd run next to InboxKit, and what each pairing covers.
Its job inside client systems.
Our sending inboxes come from InboxKit. Provisioned Google and Microsoft mailboxes with DNS and warmup handled, ready to plug into SmartLead.
Pricing, without the fiction.
From the InboxKit pricing page · verified July 17, 2026
- 10 mailbox slots
- Official admin panel per domain with 2FA
- Real-time monitoring and alerts
- 24+ platform integrations
- Unlimited team members and workspaces
- Full API access with webhooks
- 30 mailbox slots
- Everything in Professional
- Lower per-mailbox cost (~$2.70/mailbox)
- 100 mailbox slots
- Everything in Professional
- Lowest per-mailbox cost (~$2.50/mailbox)
- Dedicated Slack support instead of email/chat
Entry cost is $31/month for 10 mailbox slots on the Professional plan, moving to $81/month for 30 slots (Agency) and $250/month for 100 slots (Enterprise). Per-mailbox cost drops as slot count rises, from roughly $3.10 down to $2.50, so the low advertised rate only shows up at the top tier. Warmup is not included in the base price: it's a separate $3/mailbox/month add-on. Azure tenants add $30/tenant on top of plan cost. Additional mailboxes past a plan's slot count bill individually at $2.50-$3.10 each on annual billing; monthly billing runs higher, up to about $3.50 on Professional. Quarterly and annual billing advertise up to 20% savings, but the page does not spell out the exact discounted rates.
Choose it, or skip it.
Choose it if
- Agencies running several client sending domains that need mailboxes provisioned in bulk without touching DNS records by hand.
- Teams that want Google Workspace and Microsoft 365 (or Azure) mailboxes managed from one dashboard instead of three vendor logins.
- Anyone scaling past 30+ mailboxes who wants isolated per-domain admin panels so one bad domain doesn't drag down the rest.
- Teams that want warmup and blacklist monitoring available as paid add-ons in the same dashboard rather than stitched together from separate tools.
Skip it if
- Solo senders running 2-3 mailboxes; per-mailbox add-on fees (warmup, InfraGuard) add up faster than one manual Workspace setup.
- Teams that want sequencing and inbox provisioning in a single product; InboxKit only handles the mailboxes, not sending logic.
- Buyers expecting the advertised per-mailbox floor at low volume; that rate only shows up on the 100-slot Enterprise plan.
If not InboxKit, then what.
- Mailforgefrom $3/mailbox/mo (billed yearly, min 10 mailboxes) + $14/yr per domain; usage-based
Pick instead when you want hosted domains plus mailboxes bundled together rather than mailbox provisioning alone.
- Maildosofrom $0.49/mailbox in bulk; typical entry ~$75/mo for 30 mailboxes ($2.50 each)
Pick instead for pre-warmed mailboxes out of the gate rather than running warmup as a separate add-on.
- ScaledMailfrom $3.50/mailbox/mo (Google Workspace); Outlook $50/domain/mo; SMTP $3.75/domain/mo — reporting add-on extra
Pick instead if managed, pre-warmed Google Workspace and Microsoft 365 inboxes matter more than dashboard-driven self-service.
- InframailUnlimited plan from $129/mo flat (also $327/mo Agency Pack, $499/mo + $3,497 setup DFY tier); price increase planned Jul
Pick instead for unlimited inboxes on dedicated IPs rather than tiered plans priced per mailbox above a slot allowance.
Asked in real client work.
How does InboxKit's pricing actually scale with mailbox count?
The three monthly plans set a slot count and a base fee: Professional is $31/mo for 10 slots, Agency is $81/mo for 30 slots, Enterprise is $250/mo for 100 slots. That works out to roughly $3.10, $2.70, and $2.50 per mailbox respectively, so the per-mailbox cost drops as commitment size goes up. Additional mailboxes beyond a plan's slots are billed at $2.50 to $3.10 each on annual billing, more on monthly.
Does InboxKit support both Google Workspace and Microsoft 365?
Yes. InboxKit provisions Google Workspace, Microsoft 365, and Microsoft Azure mailboxes from the same dashboard, with automated DNS setup (SPF, DKIM, DMARC) and app password generation for each. Azure tenants are billed separately at $30 per tenant on top of the plan price.
Is email warmup included in the mailbox price or billed separately?
It's a separate add-on at $3 per mailbox per month, layered on top of whichever plan you're on. Warmup ramps sending volume per mailbox independently (roughly 2 to 40 emails/day) and tracks inbox versus spam placement in real time, so factor it into the total cost rather than assuming it's bundled.
What happens if you need more mailboxes than a plan's slot count?
Slots are the plan ceiling, not a hard cap: Professional caps at 10, Agency at 30, Enterprise at 100, and additional mailboxes past that slot count are billed individually at $2.50 to $3.10 each on annual billing, more on monthly. Teams that expect to keep growing past a few hundred mailboxes should size against the Enterprise tier up front rather than paying the higher per-mailbox add-on rate repeatedly.
Does InboxKit send emails, or just provide the mailboxes?
Just the mailboxes and the infrastructure around them (DNS, warmup, monitoring, admin panels). Sending and sequencing happen in a separate outreach tool that connects to the mailboxes via API, webhook, or app password. InboxKit lists 24+ platform integrations for that connection but does not run campaigns itself.