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InboxKit Pricing: Complete Breakdown and Calculator (2026)
By Mohit MimaniPublished on: Mar 30, 2026 · 10 min read · Last reviewed: Mar 2026
TL;DR
InboxKit charges one flat rate per mailbox with no plans and no included slots: $3.00/mo monthly, $2.70 quarterly, $2.50 annual. Warmup is a $3/mailbox/mo add-on and InfraGuard monitoring is included. Here is the complete cost breakdown.
InboxKit Pricing Overview
InboxKit uses a flat per-mailbox model. There is one rate, it applies at every volume, and the billing cycle is the only discount:
| Billing Cycle | Per Mailbox | Minimum | 10 Mailboxes | 100 Mailboxes |
|---|---|---|---|---|
| Monthly | $3.00 | none | $30/mo | $300/mo |
| Quarterly | $2.70 | none | $27/mo | $270/mo |
| Annual | $2.50 | none | $25/mo | $250/mo |
There is no base fee and no included-slot allowance, so your bill is simply mailboxes x rate. Mailboxes are charged from a prepaid wallet on each mailbox's own renewal date.
This is fundamentally different from competitors like Primeforge ($29/mo platform fee) or Instantly ($30-97/mo platform fee) that charge you before you even create a single mailbox.
Core Pricing Breakdown
Here is the complete pricing table:
| Billing Cycle | Per Mailbox | Minimum | Saving vs Monthly |
|---|---|---|---|
| Monthly | $3.00/mailbox/mo | none | — |
| Quarterly | $2.70/mailbox/mo | none | 10% |
| Annual | $2.50/mailbox/mo | none | 17% |
| Add-On / Service | Price | Notes |
|---|---|---|
| Warmup | $3.00/mailbox/mo | Isolated warmup network |
| Azure Domain | $30/domain | Up to 100 mailboxes per domain |
| Domain Registration | From $2/year | DNS auto-configured |
| InfraGuard Monitoring | Per-domain pricing | Blacklists, DNS, reputation, auto-pause |
| Inbox Placement Tests | Per-test from wallet | Seed-based testing |
The rate covers both Google Workspace (US-IP) and Microsoft 365 mailboxes. Annual billing reduces costs further (e.g., Annual: $2.50/mailbox/mo/additional). As shown on the InboxKit pricing page (see screenshot above), everything is transparent. There are no hidden fees beyond the plan price, no overage charges, and no annual lock-in.
Cost Calculator: Common Setups
| Setup | Mailboxes | Mailbox Cost (monthly) | Warmup ($3/ea) | Monthly Total |
|---|---|---|---|---|
| Starter | 10 | 10 x $3.00 = $30 | $30 | $60/mo |
| Growth | 25 | 25 x $3.00 = $75 | $75 | $150/mo |
| Scale | 50 | 50 x $3.00 = $150 | $150 | $300/mo |
| Agency | 100 | 100 x $3.00 = $300 | $300 | $600/mo |
| Large | 200 | 200 x $3.00 = $600 | $600 | $1,200/mo |
On annual billing every mailbox figure above drops to $2.50, so 200 mailboxes is $500/mo rather than $600.
- 200 mailboxes: 200 x $3.00 = $600
- Warmup: $3.00 x 200 = $600.00
- Total: $1,200/mo (before domains and InfraGuard)
Google Workspace and Microsoft 365 mailboxes are the same price. Domain registration, InfraGuard monitoring, and inbox placement tests are additional costs. DNS automation and 24+ sequencer integrations are included.
InboxKit vs Competitor Pricing
50 Mailbox cost comparison (monthly):
| Provider | Plan / Pricing | 50 Mailbox Total | Notes |
|---|---|---|---|
| InboxKit | 50 x $3.00 flat (no plan fee) | $150/mo | Google + Microsoft, InfraGuard included |
| ZapMail | Growth $99/mo (30 incl.) + 20 x $3.25 | $164/mo | Google + Microsoft 365, no monitoring, no Azure |
| Maildoso | ~$2.50/mailbox flat | ~$125/mo | Shared infrastructure |
| Primeforge | $3.50-4.50/mailbox | $175-225+ | Varies by plan |
| Instantly | ~$4.00/mailbox + platform | $230-297 | $30-97/mo platform fee |
ZapMail still sells plan tiers with included slots; InboxKit charges a flat per-mailbox rate with no plan fee, which is cheaper at volumes that fall between a competitor's tiers.
What is included vs. extra:
| Feature |  InboxKit |  ZapMail |  Primeforge |  Mailforge |
|---|---|---|---|---|
| Microsoft 365 | Yes | Yes | Yes | No |
| Azure Mailboxes | Yes ($30/tenant, 100 mailboxes) | No | No | No |
| Warmup | $3/mailbox/mo (isolated) | Pre-warmed option ($6-8/mailbox premium) | Warmforge $2/mailbox | Warmforge $2/mailbox |
| Monitoring | InfraGuard (per-domain) | None | Infraforge $1.50/mailbox | Infraforge $1.50/mailbox |
| Inbox Testing | Wallet-based | None | None | None |
| DNS Automation | Included | Semi-automated | Partial | None |
| Integrations | 24+ sequencers | 5 | 4 | 3 |
ROI Analysis
The real question is cost per email delivered to inbox.
- 100 mailboxes sending 40 emails/day = 4,000 emails/day
- 82% inbox rate = 3,280 inbox deliveries/day
- Mailboxes: 100 x $3.00 = $300/mo
- Monthly warmup cost: $3.00 x 100 = $300
- Total: $600/mo (before InfraGuard)
- Cost per inbox delivery: $600 / (3,280 x 30) = $0.0061
- Same volume: 3,000 inbox deliveries/day
- Monthly cost: ~$500
- Cost per inbox delivery: $500 / (3,000 x 30) = $0.0056
The per-delivery costs are in a similar range. InboxKit's advantage is the isolated warmup quality (which produces higher inbox placement) and InfraGuard monitoring (which catches issues before they tank deliverability). For teams where every percentage point of inbox placement matters, InboxKit's total value proposition is stronger.
Getting Started
- 1Create your account at inboxkit.com
- 2Choose a billing cycle (monthly, quarterly or annual — the rate is $3.00, $2.70 or $2.50)
- 3Buy domains and create as many mailboxes as you need
- 4Activate warmup ($3.00/mailbox/mo) and InfraGuard (per-domain pricing)
- 5Start sending after 14-21 days of warmup
No contracts, no plan fees and no minimum. Scale up or down anytime by adding or removing mailboxes.
Frequently Asked Questions
InboxKit charges one flat rate per mailbox — $3.00/mo monthly, $2.70 quarterly, $2.50 annual — with no plan fee and no included slots. There are no hidden platform fees. You pay for the mailboxes you create plus optional add-ons like warmup.
There is no plan and no minimum — mailboxes are $3.00 each on monthly billing, so 100 mailboxes is $300/mo. On annual billing the rate drops to $2.50, making the same 100 mailboxes $250/mo.
No. Warmup is a separate add-on at $3.00/mailbox/mo on top of the mailbox rate. Warmup uses an isolated network for higher quality results compared to shared pools used by competitors.
Google Workspace direct costs $7.20/month per user, and you handle DNS setup, warmup, and monitoring yourself. InboxKit is one flat rate per mailbox — $3.00/mo monthly, down to $2.50 on annual billing, with automated DNS and warmup available at $3/mailbox/mo as an add-on.
Sources & References
- 1
InboxKit Pricing Page(2026)
- 2
- 3
Google Workspace Pricing(2026)
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