InboxKit Pricing 2026: Plans, Add-Ons and Real Cost

InboxKit charges $3.00 per Google Workspace or Microsoft 365 mailbox a month on monthly billing, $2.70 on quarterly and $2.50 on annual. There is no minimum and no volume tier: one mailbox and five hundred cost the same per mailbox. Warmup is an add-on at $3 per mailbox a month. There is no sequencer. Domains start at $2 a year.

Prices below are from inboxkit.com/pricing and InboxKit's pricing guide, checked September 28, 2026.

InboxKit Plans and Prices

InboxKit has no plans and no included slots. You pay per mailbox from a prepaid wallet: "One price per mailbox, paid from your wallet. No plans, no slots, no minimum."

The pricing page puts it plainly: "The rate is the same at every volume — one mailbox and five hundred mailboxes are both $3.00/month, so there is no tier to climb." There are no setup fees.

What the Mailbox Price Includes

• A Google Workspace or Microsoft 365 mailbox, with SPF, DKIM and DMARC automated. Orders are done in 30 to 120 minutes.

• An admin panel with 2FA (one per domain).

• Real-time monitoring and alerts, with per-mailbox analytics.

• 24+ integrations, plus app passwords for any SMTP tool.

• A full REST API with webhooks.

• Unlimited team members and workspaces.

• Email and chat support.

Not included: warmup, a sequencer, blacklist monitoring and placement tests.

Costs on Top of the Mailbox Price

InboxKit's own pages disagree on InfraGuard: the pricing guide's summary says monitoring is included, while its table and the pricing page list it as a per-domain add-on. We follow the pricing page.

Domains can be transferred out for free after the 60-day registrar lock: "InboxKit does not charge any fee to transfer a domain away from InboxKit." Domains are not refunded.

There is no traditional free trial: "InboxKit does not offer a traditional free trial, but there is no minimum and no plan to commit to, so you can start with a single mailbox for $3.00/month and scale from there." Subscription fees "are generally non-refundable", and if you close your account, "any remaining wallet balance is forfeited and will not be refunded."

What InboxKit Costs at 25, 100 and 400 Mailboxes

Monthly cost on monthly billing. The full setup adds warmup and a sequencer: we use the cheapest Instantly plan that covers 25 emails a day per mailbox (method), because Instantly includes warmup in the plan, so InboxKit's $3 warmup add-on is not needed. Domains are left out.

If you use InboxKit's warmup instead of the sequencer's, add $3 per mailbox a month: $75 at 25 mailboxes, $300 at 100, $1,200 at 400. On annual billing the mailbox line drops to $2.50 each: $62.50, $250 and $1,000.

InboxKit vs Outreach2day

At every size in the table, the full setup costs less with us, and our $2.50 is the monthly price, with warmup and a sequencer included. InboxKit reaches $2.50 only on annual billing, for the mailbox alone. Differences to know: InboxKit sells Google Workspace and Microsoft 365 mailboxes (ours are SMTP/IMAP) and has no minimum; ours starts at 12. Neither of us offers a free trial. Other options are in InboxKit alternatives. InboxKit is fifth of ten in our best cold email infrastructure providers list.

For the rest of the picture, our InboxKit review covers the wallet billing, refund terms, API and support with sources. InboxKit against another Google and Microsoft seller is in Zapmail vs InboxKit, and against an SMTP vendor in Mailforge vs InboxKit.

FAQ

How much does InboxKit cost per mailbox?

$3.00 a month on monthly billing, $2.70 on quarterly and $2.50 on annual, the same at every volume. Azure tenants are $30 a month each for up to 100 mailboxes.

Does InboxKit include warmup?

No. Warmup is a $3 per mailbox a month add-on. If your sequencer includes warmup, as Instantly and Smartlead do, you can use that instead.

What does InboxKit cost with its own warmup?

$6 per mailbox a month on monthly billing: $3 for the mailbox and $3 for warmup. At 100 mailboxes that is $600 a month before domains and a sending tool; on annual billing the mailbox part drops to $250, so $550.

Is there a minimum order?

No. You can start with one mailbox, paid from a prepaid wallet.

Does InboxKit offer refunds?

Subscriptions are generally non-refundable, domains are never refunded, and unused wallet balance is forfeited when you close the account, per its refund policy.

Sources

Checked September 28, 2026:

• InboxKit pricing: mailbox prices, Azure tenants, add-ons, trial.

• InboxKit pricing guide: domains, placement tests, InfraGuard.

• InboxKit home page: mailbox types, setup time.

• InboxKit refund policy: refunds, wallet, domain transfers.