InboxKit

InboxKit is a cold email infrastructure platform trusted by organizations including PwC, Zendesk, Merck Group, and Smartlead for provisioning official Google Workspace, Microsoft 365, and Azure mailboxes built specifically for outbound outreach.

The platform automates every technical layer of email infrastructure, including SPF, DKIM, and DMARC configuration, US-based IP assignment, AI-powered warmup, domain isolation, and real-time deliverability monitoring, all accessible from a single dashboard.

InboxKit is best suited for agencies, SDR teams, and outreach platforms that need to scale mailboxes quickly without manual DNS work, with plans starting at $39 per month.

Top Features

• Official Google Workspace, Microsoft 365, and Azure mailbox provisioning
• Automated SPF, DKIM, and DMARC configuration with zero manual setup
• US-based IP infrastructure for improved sender reputation
• Dedicated isolated admin panel per domain to prevent cross-contamination
• AI-powered 14-day warmup with smart volume ramping from 2 to 40 emails per day
• Bulk mailbox creation via CSV import or AI generation for agencies
• 15+ native integrations including Instantly, Smartlead, Lemlist, Apollo, and HubSpot
• InfraGuard protection suite with blacklist monitoring, DNS watchdog, and inbox placement tests

Pricing

InboxKit offers three plans: the Professional plan at $39 per month includes 10 mailboxes with add-ons at $3.50 each; the Agency plan at $99 per month includes 30 mailboxes with add-ons at $3.25 each; and the Enterprise plan at $299 per month includes 100 mailboxes with add-ons at $2.99 each. Every plan includes automated DNS setup, official Google and Microsoft accounts, 95% inbox delivery, full API and webhook access, unlimited users, and 24/7 priority support. Warmup is available as a separate add-on at $3 per mailbox per month, and InfraGuard monitoring is available with the first month free.

What Makes InboxKit Different from Standard Email Providers

Most cold email practitioners set up Google Workspace or Microsoft 365 accounts manually, which involves navigating registrar DNS panels, waiting for record propagation, and hoping configurations are correct before sending.

InboxKit removes that entire process by acting as an official Google Cloud partner that provisions and configures mailboxes on your behalf.

The result is a fully authenticated, reputation-clean mailbox ready to send in under 10 minutes rather than hours or days.

A less obvious but important distinction is the domain isolation architecture. Each domain you manage inside InboxKit receives its own dedicated admin panel.

If one domain gets flagged, suspended, or blacklisted, the damage does not spread to other domains in your account.

This is particularly valuable for agencies managing outreach across multiple clients, where a single reputation incident on one client's domain could otherwise contaminate shared infrastructure.

InboxKit also recently added Azure mailboxes as an enterprise-grade Microsoft 365 option, expanding beyond standard Workspace and 365 accounts.

This gives larger teams access to Azure-hosted infrastructure with the same automated setup and warmup features.

InboxKit Integrations and Sending Workflow

InboxKit is not a sending tool. It is infrastructure that sits behind your existing outreach platform. Once mailboxes are provisioned and warmed, you connect them to your sequencer of choice via SMTP or API.

The platform supports over 15 tools natively, including Instantly, Smartlead, Lemlist, Apollo, HubSpot, Salesforce, and SalesForge.

This separation of infrastructure from sequencing is intentional. Teams that already have a preferred sending tool do not need to migrate their workflows.

They simply point their sequencer at InboxKit-managed mailboxes and benefit from improved deliverability without changing how they write or schedule campaigns.

Full API access and webhook support also allow engineering teams to build custom integrations or automate mailbox provisioning as part of a larger outreach stack.

InboxKit Free Tools

InboxKit provides 18 free email tools that require no account or sign-up to use.

These cover the full range of pre-send diagnostics, including a deliverability score checker, SPF and DKIM record generators and validators, DMARC record builder, DNS validator, domain scanner, blacklist and reputation checker, email header analyzer, spam word checker, BIMI record tools, MTA-STS checker, and a mailbox calculator that estimates how many inboxes you need based on your sending volume goals.

These tools are useful for diagnosing deliverability problems on existing domains before migrating to InboxKit, or for auditing domains you plan to purchase for outreach.

InfraGuard and Ongoing Deliverability Protection

Beyond initial setup, InboxKit offers an add-on called InfraGuard that provides continuous monitoring after your mailboxes are live.

It checks your domains against 50 or more blacklist providers every six hours, watches for DNS and authentication record changes, tracks bounce rates and sends alerts when thresholds are crossed, and runs inbox placement tests across major email providers.

Reports can be delivered to Slack for teams that want real-time visibility without logging into a dashboard. The first month of InfraGuard is free for new users.

Who Should Not Use InboxKit

InboxKit is a pure infrastructure tool. It does not include prospect list building, email copywriting, sequence management, A/B testing, or LinkedIn outreach.

Teams looking for an all-in-one platform that handles both infrastructure and campaign execution will need to pair InboxKit with a separate sequencing tool.

Additionally, all mailboxes are provisioned on US-based IPs, which may affect deliverability for campaigns targeting audiences in regions where US IP origins are treated with higher suspicion by local mail servers.

There is also no free plan. Every user must purchase a paid subscription to access mailboxes, which means InboxKit is not suitable for individuals who want to test cold email infrastructure at zero cost before committing.

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