Agencies buy infrastructure differently to a single sender. You buy it again and again, for clients with different volumes, and you carry the blame when a set burns. So the questions that matter are not just price per inbox. They are what a unit actually includes, how fast you can replace it, and how much of the setup lands on your team.
We compared ten providers on the things agencies ask us about most. Every competitor fact below comes from that provider's own website, checked in October 2026, with sources at the end. We are one of the providers, so we have kept our own entry to the same facts-only standard.
The short version
| Provider | Microsoft | Google Workspace | Domain in the price | Done-for-you |
|---|---|---|---|---|
| Frostmailer | Azure, €30 per tenant (25, 50 or 100 inboxes) | €3.00 to €2.50 per inbox | Yes on Azure (.com) | Yes, from €1,000 a month |
| InboxKit | Azure $30 per tenant (up to 100), or M365 $3.00 per mailbox | $3.00 per mailbox ($2.50 annual) | Not stated | No |
| Primeforge | M365 $4.50 per slot | $4.50 per slot | No, $14 a year per .com | No |
| Hypertide | Entra $25 per domain (25 inboxes) | $3.30 per inbox | Yes on Entra | No |
| ScaledMail | Outlook $50 per domain (25 mailboxes) | $3.50 per mailbox | Yes on Outlook | Setup done for you, no price listed |
| Zapmail | M365 per seat | Plans per seat | No | No |
| Premium Inboxes | M365, same tiers as Google | $3.50 to $2.80 per inbox | No, bring your own | Managed tier, $7,500 a month |
| Inframail | Flat $147 a month, up to 400 mailboxes | Not offered | No, $5 per domain | $797 a month, 3-month minimum |
| Mailforge | Not offered (shared IP pool, $3 per slot) | Not offered | No, $14 a year per .com | No |
| Infraforge | Not offered (dedicated IPs, $4 per slot) | Not offered | No, $14 a year per .com | No |
Frostmailer
Microsoft Azure tenants at €30 a month, where one tenant is a .com domain plus your choice of 25, 50 or 100 inboxes, same price. Each inbox sends 2 to 3 emails a day, so volume comes from breadth. Google Workspace full admin runs €3.00 falling to €2.50 per inbox at 500+, with your own domains. Pre-warmed stock is €50 a tenant on Azure (minimum 2) and €8 an inbox on Google with the domain included. There is a REST API and an MCP server on every account, and delivery takes 10 to 24 hours.
Best for: agencies sending most of their volume to Outlook inboxes, and agencies that want the whole system built. Build and Release sets up domains, mailboxes, copy, campaigns and the first month of leads from €1,000 a month, then hands it to you after 14 days.
InboxKit
One flat rate with no plans, base fee or minimum: $3.00 per mailbox a month for both Google and Microsoft 365, or $2.50 on annual billing. Azure is $30 a tenant for up to 100 mailboxes. Pre-warmed mailboxes are $6, $7 or $9 depending on how long they have been warmed, and pre-warmed Azure tenants $30 to $50. Warm-up is a $3 per mailbox add-on. There is a REST API and an MCP server.
Best for: agencies that want to self-serve both providers from one wallet with no minimum.
Primeforge
The Forge family's product for real Google Workspace and Microsoft 365 mailboxes, at $4.50 per mailbox slot a month with a minimum of 10 slots. Domains are extra at $14 a year per .com. Setup is automated and quoted at about 30 minutes.
Best for: agencies already using Salesforge or Warmforge who want everything in one ecosystem.
Hypertide
Microsoft Entra at $25 a domain a month with 25 inboxes and the domain included, and Google Workspace at $3.30 an inbox. Setup is quoted at 4 to 6 hours. No pre-warmed product is listed.
Best for: small Microsoft orders where 25 inboxes per domain is enough.
ScaledMail
Google Workspace at $3.50 a mailbox, and Outlook at $50 a domain for 25 mailboxes with the domain included. ScaledMail says it handles DNS, domains and inbox setup for you, with delivery quoted at 24 to 72 hours.
Best for: agencies that want setup handled but are happy to run campaigns themselves.
Zapmail
Google Workspace and Microsoft 365 mailboxes priced per seat, with pre-warmed inboxes, an API and an MCP server. Domains are bought through Zapmail or brought in, and the setup keeps your nameservers with Zapmail. Zapmail merged its Google and Microsoft plans on 13 October 2026, so check its site for current prices.
Best for: Google-first agencies that want pre-warmed inboxes and lots of add-ons in one dashboard.
Premium Inboxes
Google Workspace and Microsoft 365 on one price list, $3.50 to $2.80 per inbox by volume, with unlimited replacement inboxes. You bring your own domains. A managed tier runs at $7,500 a month by application.
Best for: agencies that replace inboxes often and already own their domains.
Inframail
Flat plans on Microsoft-backed infrastructure: $147 a month for up to 400 mailboxes with a dedicated IP, or $387 for up to 1,000. No Google Workspace. A done-for-you plan is $797 a month with a 3-month minimum.
Best for: high-volume agencies that want unlimited inboxes on one bill.
Mailforge and Infraforge
Neither sells Google or Microsoft mailboxes. Mailforge runs on a shared IP pool at $3 a slot, minimum 10. Infraforge uses dedicated servers with a dedicated IP per mailbox at $4 a slot, minimum 10. Domains are $14 a year each on both.
Best for: high volume at a low price per mailbox, on infrastructure outside Google and Microsoft.
How to choose as an agency
- Look at your clients' prospects first. If most of them read email in Outlook, Microsoft infrastructure lands better and costs less per send.
- Compare what a unit includes, not the headline. A tenant with a .com and 50 inboxes is a different purchase to 50 mailbox slots plus 50 domains bought separately.
- Price the replacement, not just the first order. Sets decay. Pre-warmed stock and a rotation plan decide whether a client notices a dip.
- Decide how much setup your team should own. DNS, warm-up, copy and campaign build are hours per client. Some providers stop at the mailbox; a few build the whole thing.
For the maths on how many inboxes and domains a given volume needs, see How Many Mailboxes Do You Need for Cold Email?, and for Azure versus Google per client, Best Cold Email Mailboxes for Agencies.
Sources, checked October 2026: inboxkit.com/pricing, primeforge.ai/pricing, mailforge.ai/pricing, infraforge.ai/pricing, scaledmail.com/pricing, hypertide.io/entra, hypertide.io/google, zapmail.ai and its help centre, premiuminboxes.com/pricing-page, inframail.io. Prices are in each provider's own currency and change often, so check the provider's site before buying.
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