Zapmail vs InboxKit: both say $2.50 for Google and Microsoft mailboxes; warm-up makes the difference
Both reach $2.50 a mailbox only on yearly billing. Zapmail sells plans of 10, 30 and 100 with warm-up handled; InboxKit sells single mailboxes from a wallet and charges $3 a mailbox for warm-up. Zapmail has an MCP server; InboxKit has none.
- Warm-up and sending included
- $2.50 a mailbox, 12 minimum
- Month-to-month billing
Zapmail
InboxKit
- Price per mailbox
- from $2.50 (Pro, yearly); $2.99 on monthly Profrom $2.50 (annual billing); $3 monthly
- Smallest order
- Starter: 10 mailboxes, $39 a monthNone; one mailbox
- Mailbox types
- Google, MicrosoftGoogle, Microsoft
- Warm-up
- Handled by Zapmail per its FAQ; no separate price or schedule publishedIsolated Warmup add-on, $3 a mailbox a month
Zapmail vs InboxKit, line by line
Each cell links to the vendor's page it comes from.
| Feature | Zapmail | InboxKit |
|---|---|---|
| Smallest order | Starter: 10 mailboxes, $39 a month source (opens the vendor's page in a new tab) | None; one mailbox source (opens the vendor's page in a new tab) |
| Setup time | 5 minutes on average, per the home page source (opens the vendor's page in a new tab) | Orders done automatically in 30–120 minutes; pro-rata credit if a delivery is over 48 hours late source (opens the vendor's page in a new tab) |
| Mailbox types | Google Workspace and Microsoft 365 on US or EU IPs; one domain per workspace source (opens the vendor's page in a new tab) | Google Workspace on US IPs, Microsoft 365 and Azure-tenant Microsoft mailboxes source (opens the vendor's page in a new tab) |
| Domains | Bought through Zapmail (10+ extensions) or your own; bought domains belong to you source (opens the vendor's page in a new tab) | Your own domains or registered through InboxKit; domains are non-refundable source (opens the vendor's page in a new tab) |
| Sending limits | No daily cap published for standard plans; pre-warmed mailboxes start at 20 a day source (opens the vendor's page in a new tab) | No hard limit on the product pages; its guides suggest 40–50 emails per mailbox a day source (opens the vendor's page in a new tab) |
| Warm-up | IncludedHandled by Zapmail per its FAQ; no separate price or schedule published source (opens the vendor's page in a new tab) | Partly, or at extra costIsolated Warmup add-on, $3 a mailbox a month source (opens the vendor's page in a new tab) |
| Sequencers | 23 OAuth platforms incl. Instantly, Smartlead, Lemlist, Saleshandy, Apollo; one-click to ReachInbox, Instantly, Smartlead, Reply.io source (opens the vendor's page in a new tab) | 24+ integrations incl. Instantly, Smartlead, Apollo, Reply, Lemlist, EmailBison; app passwords for others source (opens the vendor's page in a new tab) |
| API | IncludedPublic API with webhooks; listed on Pro plans source (opens the vendor's page in a new tab) | IncludedREST API with webhooks on every mailbox: orders, domains, mailboxes, exports, billing source (opens the vendor's page in a new tab) |
| MCP server | IncludedHosted MCP server (OAuth 2.1) with 134 tools for domains, mailboxes, workspaces, billing source (opens the vendor's page in a new tab) | Not includedNone found on the site or in the API docs source (opens the vendor's page in a new tab) |
| Support | Email and help center; priority support on Pro; hours not published source (opens the vendor's page in a new tab) | 24/7 chat, email and phone; enterprise Slack with a one-hour SLA source (opens the vendor's page in a new tab) |
| Refunds | No refunds, except duplicate billing or service not set up within 7 business days source (opens the vendor's page in a new tab) | Non-refundable, no pro-rata refunds; exceptions for duplicate billing, non-delivery or a 72-hour outage source (opens the vendor's page in a new tab) |
| Trial | Not published source (opens the vendor's page in a new tab) | No free trial; start with one mailbox source (opens the vendor's page in a new tab) |
Smallest order
- Zapmail
- Starter: 10 mailboxes, $39 a month source (opens the vendor's page in a new tab)
- InboxKit
- None; one mailbox source (opens the vendor's page in a new tab)
Setup time
- Zapmail
- 5 minutes on average, per the home page source (opens the vendor's page in a new tab)
- InboxKit
- Orders done automatically in 30–120 minutes; pro-rata credit if a delivery is over 48 hours late source (opens the vendor's page in a new tab)
Mailbox types
- Zapmail
- Google Workspace and Microsoft 365 on US or EU IPs; one domain per workspace source (opens the vendor's page in a new tab)
- InboxKit
- Google Workspace on US IPs, Microsoft 365 and Azure-tenant Microsoft mailboxes source (opens the vendor's page in a new tab)
Domains
- Zapmail
- Bought through Zapmail (10+ extensions) or your own; bought domains belong to you source (opens the vendor's page in a new tab)
- InboxKit
- Your own domains or registered through InboxKit; domains are non-refundable source (opens the vendor's page in a new tab)
Sending limits
- Zapmail
- No daily cap published for standard plans; pre-warmed mailboxes start at 20 a day source (opens the vendor's page in a new tab)
- InboxKit
- No hard limit on the product pages; its guides suggest 40–50 emails per mailbox a day source (opens the vendor's page in a new tab)
Warm-up
- Zapmail
- IncludedHandled by Zapmail per its FAQ; no separate price or schedule published source (opens the vendor's page in a new tab)
- InboxKit
- Partly, or at extra costIsolated Warmup add-on, $3 a mailbox a month source (opens the vendor's page in a new tab)
Sequencers
- Zapmail
- 23 OAuth platforms incl. Instantly, Smartlead, Lemlist, Saleshandy, Apollo; one-click to ReachInbox, Instantly, Smartlead, Reply.io source (opens the vendor's page in a new tab)
- InboxKit
- 24+ integrations incl. Instantly, Smartlead, Apollo, Reply, Lemlist, EmailBison; app passwords for others source (opens the vendor's page in a new tab)
API
- Zapmail
- IncludedPublic API with webhooks; listed on Pro plans source (opens the vendor's page in a new tab)
- InboxKit
- IncludedREST API with webhooks on every mailbox: orders, domains, mailboxes, exports, billing source (opens the vendor's page in a new tab)
MCP server
- Zapmail
- IncludedHosted MCP server (OAuth 2.1) with 134 tools for domains, mailboxes, workspaces, billing source (opens the vendor's page in a new tab)
- InboxKit
- Not includedNone found on the site or in the API docs source (opens the vendor's page in a new tab)
Support
- Zapmail
- Email and help center; priority support on Pro; hours not published source (opens the vendor's page in a new tab)
- InboxKit
- 24/7 chat, email and phone; enterprise Slack with a one-hour SLA source (opens the vendor's page in a new tab)
Refunds
- Zapmail
- No refunds, except duplicate billing or service not set up within 7 business days source (opens the vendor's page in a new tab)
- InboxKit
- Non-refundable, no pro-rata refunds; exceptions for duplicate billing, non-delivery or a 72-hour outage source (opens the vendor's page in a new tab)
Trial
- Zapmail
- Not published source (opens the vendor's page in a new tab)
- InboxKit
- No free trial; start with one mailbox source (opens the vendor's page in a new tab)
Zapmail and InboxKit prices
Zapmail
| Plan | Price | Mailboxes | Per mailbox | Billing | Includes |
|---|---|---|---|---|---|
| Starter | $39 a month | 10 (extra $3.50) | $3.90 | monthly | 3 placement-test and 3 AI Insights credits a month source (opens the vendor's page in a new tab) |
| Growth | $99 a month | 30 (extra $3.25) | $3.30 | monthly | 10 test and 10 AI Insights credits a month source (opens the vendor's page in a new tab) |
| Pro | $299 a month | 100 (extra $3.00) | $2.99 | monthly | API access, priority support, 30 test credits a month source (opens the vendor's page in a new tab) |
| Pre-warmed Starter | $39 first month, then $24 | 3 | $8.00 | monthly | 1 domain; 12+ weeks of warm-up history source (opens the vendor's page in a new tab) |
| Pre-warmed Growth | $149 first month, then $84 | 12 | $7.00 | monthly | 4 domains source (opens the vendor's page in a new tab) |
| Pre-warmed Pro | $339 first month, then $180 | 30 | $6.00 | monthly | 10 domains source (opens the vendor's page in a new tab) |
InboxKit
| Plan | Price | Mailboxes | Per mailbox | Billing | Includes |
|---|---|---|---|---|---|
| Google Workspace or Microsoft 365 | $3.00 a month | per mailbox, from 1 | $3.00 | monthly | Automated DNS, an admin panel per domain, API with webhooks source (opens the vendor's page in a new tab) |
| Azure tenant | $30 a month | up to 100 per tenant | $0.30 at 100 | monthly | Azure-hosted Microsoft mailboxes source (opens the vendor's page in a new tab) |
| Isolated Warmup | $3 a mailbox a month | per mailbox | $3.00 | monthly | Ramps from 2 to 40 emails a day source (opens the vendor's page in a new tab) |
List prices from Zapmail's pricing page and InboxKit's pricing page, checked . Taxes and card fees excluded.
Cost at 10 and 100 mailboxes
10 mailboxes, monthly: Zapmail Starter is $39. InboxKit is $30 for the mailboxes and $60 with Isolated Warmup on all of them.
100 mailboxes, monthly: Zapmail Pro is $299. InboxKit is $300, or $600 with warm-up. On yearly billing, Zapmail Pro is $250 a month and InboxKit $250 for mailboxes plus $300 for warm-up.
Below 10 mailboxes InboxKit is the only option of the two, and each mailbox renews on its own date.
Where they differ
Plans or a wallet
Zapmail bills plans with included mailboxes and extra slots at $3.50, $3.25 or $3.00; unused slots do not roll over. InboxKit has no plans: you top up a wallet and each mailbox draws its own renewal.
The wallet is flexible and unforgiving: top-ups are non-refundable and the balance is lost if you close the account.
Microsoft options
Both sell Microsoft 365 at the Google price. InboxKit also sells Azure-tenant Microsoft mailboxes at $30 a month for up to 100, the cheapest Microsoft line we found, though its pages disagree on whether the $30 is per tenant or per domain.
Automation
InboxKit's REST API with webhooks comes with every mailbox. Zapmail lists API access on Pro and adds a hosted MCP server with 134 tools, so an assistant like Claude can run orders end to end.
Refunds
Zapmail refunds duplicate charges and setups missed by 7 business days. InboxKit makes discretionary exceptions for duplicate billing, non-delivery and outages over 72 hours, and credits late deliveries.
Which one to pick
Pick Zapmail if
- You want warm-up without a second line per mailbox
- You buy 10, 30 or 100 at a time
- You want an MCP server for an AI assistant
Pick InboxKit if
- You need 1 to 9 mailboxes, or irregular counts
- You want Azure-tenant Microsoft mailboxes
- You will warm up in your sequencer and skip the add-on
Where Outreach2day fits
We sell cold email mailboxes too, so this section is ours. The comparison above does not rank us.
Our $2.50 is the monthly price and includes warm-up and a sending engine, so at 100 mailboxes the bill is $250 with nothing to add. The mailboxes are SMTP/IMAP; if Google or Microsoft accounts are a requirement, pick between Zapmail and InboxKit above.
From 1,000 mailboxes Outreach2day quotes a volume price below the per-mailbox list price of every vendor in our comparisons, including Maildoso's $0.49, with warm-up and sending in the price. Book a call and we quote your volume.
Zapmail vs InboxKit: questions
Is Zapmail or InboxKit cheaper?
Without warm-up, roughly the same: $2.99 to $3.90 a mailbox on Zapmail's monthly plans, $3.00 on InboxKit monthly, $2.50 on both with yearly billing. With InboxKit's $3 warm-up added, Zapmail costs about half at 100 mailboxes ($299 against $600).
Which has no minimum?
InboxKit. You can buy one mailbox. Zapmail's smallest plan is 10 mailboxes for $39.
Which one includes warm-up?
Zapmail, per its FAQ. InboxKit sells warm-up as an add-on at $3 a mailbox a month.
Do they have MCP servers?
Zapmail does, with 134 tools. We found none for InboxKit.
Do both sell Microsoft mailboxes?
Yes, at the Google price. InboxKit also sells Azure-tenant Microsoft mailboxes at $30 a month for up to 100.
Deliverability call
Talk to our deliverability team
Book a call with the people who run our mailbox infrastructure. We look at your current setup and tell you what to change. Running 1,000+ mailboxes? We also quote a volume price below every vendor list price in our comparisons, warm-up and sending included.
- Review your domains, DNS records and current inbox placement
- Size the setup: domains, mailboxes per domain and daily volume per mailbox
- Plan warm-up and the move from your current provider or sequencer
- 1,000+ mailboxes: a volume price per mailbox for your setup
Free call
See open times in your time zone and book on this page.
Or open the booking pageLoading available times…
Open the booking page insteadMore on Zapmail and InboxKit
- Zapmail reviewPlans, limits, warm-up, API and MCP, support and refunds, with sources
- Zapmail alternativesOptions side by side with prices and mailbox types
- Outreach2day vs ZapmailFeature table and full-setup cost
- Maildoso vs ZapmailTwo vendors side by side
- Zapmail vs Premium InboxesTwo vendors side by side
- Zapmail pricing 2026Every plan and what it costs at 25, 100 and 400 mailboxes
- InboxKit reviewPlans, limits, warm-up, API and MCP, support and refunds, with sources
- InboxKit alternativesOptions side by side with prices and mailbox types
- Mailforge vs InboxKitTwo vendors side by side
- InboxKit pricing 2026Every plan and what it costs at 25, 100 and 400 mailboxes
- Best Email Warm-Up Tools: 10 Options ComparedBlog
- Best MCP Servers for Cold Email and Outreach (2026), RankedBlog
Sources
Each vendor's own pages. Vendors change prices and plans; if something here is out of date, write to support@outreach2day.com and we will fix it.
Zapmail
- zapmail.ai
- docs.zapmail.ai/unified-provider-launch-oct-13-2026-2467594m0.md
- help.zapmail.ai/en/articles/9541225-subscriptions-plans-everything-you-need-to-know
- zapmail.ai/features/zapshield
- help.zapmail.ai/en/articles/13358418-pre-warmed-mailboxes-in-zapmail-complete-guide
- help.zapmail.ai/en/articles/10225033-supported-platforms-for-third-party-mailbox-exports
- docs.zapmail.ai/llms.txt
- docs.zapmail.ai/mcp-2408514m0
- help.zapmail.ai/en/articles/9759194-refund-policy-for-zapmail-ai
- zapmail.ai/features/placement-test
- trustpilot.com/review/zapmail.ai
- g2.com/products/zapmail/reviews
First cold emails on day 14, full volume on day 21
Add domains, create mailboxes and turn on warm-up. You see every mailbox's warm-up numbers from day one.