---
title: "Best Microsoft 365 / Outlook Inbox Provider for Cold Email [2026 Comparison]"
description: "Which provider should you buy Microsoft 365 Outlook cold email inboxes from? MailDeck, ScaledMail, Premium Inboxes, Zapmail and Primeforge compared on price per inbox, inboxes per tenant, licence tier, safe sends per day and cost per 1,000 sends."
canonical: "https://maildeck.co/blog/best-microsoft-365-outlook-inbox-provider"
last-updated: "2026-10-03"
---

> Which provider should you buy Microsoft 365 Outlook cold email inboxes from? MailDeck, ScaledMail, Premium Inboxes, Zapmail and Primeforge compared on price per inbox, inboxes per tenant, licence tier, safe sends per day and cost per 1,000 sends.

Comparison

# Best Microsoft 365 / Outlook Inbox Provider for Cold Email [2026 Comparison]

Oct 3, 2026 11 min read

Contents

Short AnswerWhy Microsoft Outlook for Cold Email at AllWhat Microsoft's Own Limits AllowWhat Actually Differs Between Outlook ProvidersThe Five Outlook Providers ComparedNormal, Premium or Mixed: Which to BuyWhen Outlook Is the Wrong AnswerSeven Questions to Ask Before You BuyFrequently Asked QuestionsMethodology

## Short Answer

If you are buying Microsoft 365 Outlook inboxes for cold email in 2026, five providers in this market actually sell them: MailDeck, [ScaledMail](https://maildeck.co/alternative/scaledmail), [Zapmail](https://maildeck.co/alternative/zapmail), [Premium Inboxes](https://maildeck.co/alternative/premium-inboxes) and [Primeforge](https://maildeck.co/alternative/primeforge). Published per-inbox pricing runs from $0.30 to $4.50, a 15x spread for what is, at the infrastructure layer, the same Microsoft IP pool.

The spread is not mostly about quality. It is driven by two things most buyers never check:

- How many inboxes the provider puts on one tenant or domain. 100 per tenant versus 25 per domain changes your domain bill by 4x before anyone has sent an email.

- Which Microsoft licence tier the inbox sits on. A Normal-licence inbox safely sends 4–5 cold emails a day; a Premium one sends 8–10. Paying per inbox without knowing the tier means you do not know what you bought.

MailDeck prices Outlook per domain, not per inbox: $30/month for a Normal tenant, $40 for Premium, $35 for Mixed, each carrying 100 inboxes and 500+ emails/day. That works out to $0.30–0.40 per inbox. Everyone else in this list prices per inbox, between $2.00 and $4.50.

## Why Microsoft Outlook for Cold Email at All

Outlook is not the best-landing inbox type — Google Workspace is. Outlook is where the volume economics are. On our platform the four types rank like this:

| Rank | Inbox type | Cold sends / day / inbox | Inboxes per domain | Cost per inbox |
|---|---|---|---|---|
| #1 Best | Google Workspace | 18–22 | 5 | ~$2.99 |
| #2 Excellent | Outlook Premium | 8–10 | 100 | ~$0.40 |
| #3 Good | Outlook Normal | 4–5 | 100 | ~$0.30 |
| #4 Variable | Private SMTP | 10–15 | 5 | ~$0.50 |

Outlook inboxes send from official Microsoft IP pools, which carry inherited reputation every major receiving server already trusts — the same reason Google Workspace lands well, and the opposite of private SMTP, where a dedicated IP starts at zero reputation. The trade is per-inbox volume: an Outlook inbox sends less per day than a Google one, and you compensate with breadth, 100 inboxes to a tenant. The full deliverability comparison is in our [Microsoft 365 vs Google Workspace benchmark](https://maildeck.co/blog/microsoft-365-vs-google-workspace-cold-email).

## What Microsoft's Own Limits Allow — and Why They Are Not Your Limits

Every provider in this market resells the same platform, so Microsoft's published limits are the ceiling all of them work under. They are worth knowing mainly because vendors quote them as though they were cold email capacity. They are not.

| Exchange Online limit | Microsoft's published value | What it means for cold email |
|---|---|---|
| Recipient rate limit | 10,000 recipients per mailbox per day | Useless as a target. A cold inbox is throttled by complaint and engagement signals long before it reaches an Exchange limit. |
| Recipients per message | 500 | Never relevant to cold email. One message addressed to many recipients is the clearest bulk signal a filter can read. |
| Message rate limit | 30 messages per minute | Orders of magnitude above safe cold pacing. We hold a 61-minute minimum interval between sends on a single inbox. |
| Maximum message size | 150 MB | Not a constraint. Attachments damage cold placement at any size. |

Those values are from Microsoft's [Exchange Online limits](https://learn.microsoft.com/en-us/office365/servicedescriptions/exchange-online-service-description/exchange-online-limits) documentation. The distance between the 10,000-per-day platform limit and the 8–10 per day a cold Outlook inbox actually tolerates is the most common misreading in this market: a provider quoting Microsoft's ceiling is describing a world with no spam filters in it. Placement is decided by the receiving side, and you can watch that side directly rather than take anyone's word for it — Microsoft exposes per-IP reputation through [SNDS](https://sendersupport.olc.protection.outlook.com/snds/), and Google through [Postmaster Tools](https://postmaster.google.com/).

The practical consequence: none of the differences that follow is about Microsoft's capacity. All five providers sell the same platform under the same ceiling. Everything that separates them sits around it.

## What Actually Differs Between Outlook Providers

Four things, in descending order of how much money they move:

### 1. Inboxes per tenant or domain

This is the hidden multiplier. Microsoft permits a large number of mailboxes on one tenant; what varies is how many a provider is willing to put there. MailDeck runs 100 inboxes per tenant. ScaledMail runs 25 per domain. For 1,000 inboxes that is 10 tenants versus 40 domains — and domain registration is billed on top at every provider in this market, so the provider with fewer inboxes per domain quietly costs you 4x the registration bill as well as the per-inbox premium.

### 2. Licence tier

Not all Outlook inboxes are configured alike. Our Premium tier carries extra deliverability configuration: it warms in 3–5 days and sustains 8–10 cold sends per inbox per day. Normal is the lower-cost way to buy breadth at 4–5 sends per inbox per day. Mixed splits a tenant 50/50. Providers that quote one per-inbox price without naming a tier are quoting an average you cannot plan against.

### 3. Whose tenant it is

Individual tenants per customer contain the blast radius: if a tenant gets flagged, it is yours alone. Pooled tenants spread one customer's complaint rate across everyone on them. MailDeck provisions individual US Microsoft tenants.

### 4. Warmup, or inventory that skips it

A standard Outlook tenant needs a warmup window before full volume. Pre-warmed inventory ships with established sender reputation and sends from day one. MailDeck sells pre-warmed Outlook tenants at $40/tenant for 100 inboxes — the same price as a Premium tenant, without the ramp.

## The Five Outlook Providers Compared

| Provider | Priced per | Published price | Per inbox | 1,000 inboxes / month |
|---|---|---|---|---|
| MailDeck — Normal | Tenant (100 inboxes) | $30/tenant | $0.30 | $300 |
| MailDeck — Mixed | Tenant (50 Normal + 50 Premium) | $35/tenant | $0.35 | $350 |
| MailDeck — Premium | Tenant (100 inboxes) | $40/tenant | $0.40 | $400 |
| MailDeck — pre-warmed | Tenant (100 inboxes) | $40/tenant | $0.40 | $400 |
| [ScaledMail](https://maildeck.co/alternative/scaledmail) | Inbox, 25 per domain | $2.00/inbox | $2.00 | $2,000 + 40 domains |
| [Premium Inboxes](https://maildeck.co/alternative/premium-inboxes) | Inbox | $2.80–4.50/inbox | $2.80–4.50 | $2,800–4,500 |
| [Zapmail](https://maildeck.co/alternative/zapmail) | Inbox | $2.99–3.50/inbox | $2.99–3.50 | $2,990–3,500 |
| [Primeforge](https://maildeck.co/alternative/primeforge) | Mailbox | $4.50/mailbox | $4.50 | $4,500 |

Normalised by what a Premium-tier Outlook inbox can safely send — 8–10 per day over 22 working days — the cost per 1,000 sends runs $2.02 at MailDeck, $10.10 at ScaledMail, $14.14–22.73 at Premium Inboxes, $15.10–17.68 at Zapmail and $22.73 at Primeforge. See Methodology for what is assumed there and what is published.

Above 20 tenants the MailDeck rate steps down on its own: Normal goes $30 → $28 (21–100) → $25 (101+), Premium $40 → $38 → $35, and the rate is set by your cumulative tenants on that product, not by the size of a single order.

Price is the easy axis. The harder one is what arrives with the inbox, because a mailbox delivered without warmup, authentication or a replacement policy costs more in labour than its unit price saves:

| Provider | Inboxes per domain or tenant | Pre-warmed option | Commitment | Notable inclusions |
|---|---|---|---|---|
| MailDeck | 100 per Outlook tenant | Yes — pre-warmed Outlook at $0.40/inbox, zero warmup | Monthly | Individual tenant per customer; free replacement of burned domains |
| [ScaledMail](https://maildeck.co/alternative/scaledmail) | 25 per domain | Not published | No contracts | Dedicated Slack channel; reporting add-on at $5/domain for Outlook |
| [Zapmail](https://maildeck.co/alternative/zapmail) | Not published | Yes — on all plans | Monthly, from $39/mo for 10 mailboxes | Google and Microsoft IPs in US and EU; setup in about 10 minutes |
| [Premium Inboxes](https://maildeck.co/alternative/premium-inboxes) | Not published | Not published | Plan tiers (Start Up, Growth) | Priced by plan tier rather than per inbox, so cost steps rather than scales |
| [Primeforge](https://maildeck.co/alternative/primeforge) | Not published | Not published | No long-term contracts; 10-slot minimum | Mailbox slots can be deleted and recreated without extra cost; two months free annually |

“Not published” means exactly that: the vendor does not state it publicly and we did not infer it. Treat every such cell as a question to ask before you buy, not as a criticism — the seven questions below are the ones whose answers move money.

## Normal, Premium or Mixed: Which to Buy

A simple decision rule:

- Buy Premium if you need volume soon. It warms in 3–5 days and sustains 8–10 sends per inbox per day. At 100,000 sends/month that is 4 Premium domains at $160/month.

- Buy Normal if you need breadth cheaply. 4–5 sends per inbox per day across more domains, which is the right shape when you want many sending identities rather than many sends from each. At 100,000 sends/month, 8 Normal domains at $240/month.

- Buy Mixed if you cannot decide. 50 Normal and 50 Premium inboxes on one tenant at $35. At 100,000 sends/month, 5 Mixed domains at $175/month.

- Buy pre-warmed if the ramp is the problem. Same $40/tenant as Premium, established sender reputation, sends from day one.

Do not exceed the per-inbox daily limits for the tier you bought. Exceeding them triggers spam classification at Microsoft's end, and recovery costs 2–4 weeks of reduced volume — reliably more expensive than the tier upgrade you were avoiding.

## When Outlook Is the Wrong Answer

- You are optimising purely for inbox placement and volume is small. Google Workspace lands better. Starter is $39/month for 10 mailboxes across 2 domains and is the cheapest honest starting point on our catalogue.

- You need very high per-inbox throughput. Private SMTP sends 10–15 per inbox per day at $0.50, with a dedicated IP — but a 100-inbox minimum order, so it is a scaling decision, not a first purchase.

- You are putting everything on one type. Don't. The ratio we recommend is roughly 50% Outlook, 30% SMTP, 20% Google; the [diversification guide](https://maildeck.co/blog/cold-email-infrastructure-diversification) explains why, and the Diversified Stack bundles from $99/month are built to that split.

## Seven Questions to Ask an Outlook Provider Before You Buy

Every one of these has a cheap answer and an expensive answer, and the expensive answer is usually silence. Ask them in writing before the first invoice.

| Question | Why it moves money | What a good answer sounds like |
|---|---|---|
| How many inboxes per tenant or domain? | The single biggest cost multiplier. 100 per tenant against 25 means 10 domains instead of 40 at 1,000 inboxes, and domain count drives registration, DNS and monitoring work. | A number, stated plainly, with the licence tier it applies to. |
| Is the tenant mine or shared? | Blast radius. A flagged shared tenant takes your sending down with other people's behaviour. | An individual tenant per customer, or an explicit explanation of what a shared tenant means for you. |
| What is your published per-inbox daily send limit? | A provider with no number has no deliverability position, and you will discover the real ceiling by burning domains. | A specific range per licence tier — ours is 4–5 on Normal, 8–10 on Premium. |
| Are inboxes warmed on arrival, and for how long? | Warmup is 5–7 days of lost sending on Outlook. Pre-warmed inventory buys that back; unwarmed inventory sold as ready burns. | Either pre-warmed inventory with a price, or a stated warmup schedule you run. |
| Who registers and authenticates the domains? | 67% of the 1,000+ cold email domains we have audited carried at least one critical authentication error. Unclear ownership of SPF, DKIM and DMARC is where that comes from. | A named owner for DNS, and records you can verify yourself. |
| What happens when a domain burns? | Domains burn in normal operation. Whether replacement is free, paid or slow decides your real cost per sending month. | A written replacement policy with a turnaround time. |
| Can I see the reputation of the IPs I send from? | Without it you cannot distinguish your own mistake from a neighbour's, which is the difference between fixing and switching. | Named pools, plus a pointer to SNDS or Postmaster Tools data you can read yourself. |

If a provider answers all seven, unit price is a fair way to choose between what is left. If they answer three, the cheap inbox is not cheap — you are taking on the unanswered four as unpriced operational risk. Our [30-minute infrastructure audit](https://maildeck.co/blog/cold-email-infrastructure-audit) walks the same ground on infrastructure you already own.

## Frequently Asked Questions

### Who is the best Microsoft 365 / Outlook inbox provider for cold email?

Five providers sell Microsoft 365 Outlook inboxes for cold email in 2026: MailDeck at $0.30-0.40 per inbox (priced per tenant at $30-40 for 100 inboxes), ScaledMail at $2.00, Premium Inboxes at $2.80-4.50, Zapmail at $2.99-3.50 and Primeforge at $4.50. The large spread comes mostly from how many inboxes each provider puts on one tenant or domain and which Microsoft licence tier the inbox sits on, not from the underlying infrastructure, which is the same official Microsoft IP pool in every case.

### How much should Microsoft 365 cold email inboxes cost?

Published 2026 rates run from $0.30 to $4.50 per inbox per month. At 1,000 inboxes that is $300/month at the low end and $4,500 at the high end. The deciding variable is inboxes per tenant: 100 per tenant means 10 tenants for 1,000 inboxes, while 25 per domain means 40 domains, and domain registration is billed on top at every provider. Compare the total of per-inbox price plus domain count, not the per-inbox price alone.

### How many cold emails can I send per Outlook inbox per day?

It depends on the licence tier. A Microsoft 365 Premium-configured inbox safely sends 8-10 cold emails per day; a Normal-licence inbox sends 4-5. Each domain carries 100 inboxes and 500+ emails per day in total. Exceeding these limits triggers spam classification at the provider level, and recovery takes 2-4 weeks of reduced volume. Any provider quoting one per-inbox price without naming a licence tier is quoting an average you cannot plan sending volume against.

### How many inboxes can you put on one Microsoft 365 tenant?

MailDeck provisions 100 inboxes per tenant on individual US Microsoft tenants. Other providers in this market run fewer: ScaledMail, for example, runs 25 inboxes per domain. This matters more than it looks, because domain registration is billed separately everywhere. For 1,000 inboxes, 100 per tenant means 10 domains to register and 25 per domain means 40 - four times the registration bill on top of a higher per-inbox price.

### Are Microsoft 365 or Google Workspace inboxes better for cold email?

Google Workspace lands best and costs the most per inbox at roughly $2.99 with 18-22 safe cold sends per inbox per day. Microsoft 365 Outlook is where the volume economics are, at roughly $0.30-0.40 per inbox with 4-5 safe sends on the Normal licence or 8-10 on Premium, and 100 inboxes per tenant. Both send from official provider IP pools with inherited reputation. Most programmes should not sit entirely on one of them; a roughly 50% Outlook, 30% SMTP, 20% Google split spreads the risk.

### What is a pre-warmed Outlook inbox and is it worth it?

A pre-warmed Outlook tenant ships with an established sender reputation, so it sends from day one instead of after a 3-5 day ramp. MailDeck sells pre-warmed Outlook tenants at $40 per tenant for 100 inboxes, the same price as a standard Premium tenant. It is worth it when the warmup window, not the price, is what is blocking a launch. Pre-warmed Google Workspace and pre-warmed private SMTP inboxes are sold out at the time of writing.

### Do Outlook cold email inboxes use shared or dedicated IPs?

Microsoft 365 Outlook inboxes send through official Microsoft IP pools, which are shared across Microsoft's customers but carry inherited reputation that every major receiving server already trusts. That is a different proposition from a shared IP pool operated by a small SMTP vendor, and from a dedicated IP, which starts at zero reputation and has to earn it. For cold email the official-pool route is usually the lower-risk one.

### What are Microsoft's actual sending limits for Exchange Online?

Microsoft publishes a recipient rate limit of 10,000 recipients per mailbox per day, a maximum of 500 recipients per message, a message rate limit of 30 messages per minute and a 150 MB maximum message size. None of those is a cold email limit. They are platform ceilings that apply equally to every reseller of Microsoft 365, and a cold inbox is throttled by complaint and engagement signals long before it reaches any of them. The safe figure for cold sending on an Outlook inbox is 8-10 per day on a Premium licence and 4-5 on Normal. Treat a provider who quotes Microsoft's 10,000 as cold capacity as a warning sign.

### What should I ask an Outlook inbox provider before buying?

Seven things, all of which should be answered in writing: how many inboxes sit on one tenant or domain; whether the tenant is yours alone or shared; the published per-inbox daily send limit by licence tier; whether inboxes are warmed on arrival and for how long; who registers and authenticates the domains; what happens when a domain burns, and how fast; and whether you can see the reputation of the IP pools you send from. Inboxes-per-tenant and the replacement policy move the most money. A provider who will not state a per-inbox daily limit has no deliverability position, and you will find the real ceiling by burning domains.

## Methodology

MailDeck prices, inbox counts per tenant and safe sends per inbox per day come from our published [pricing page](https://maildeck.co/pricing) and from platform data: 833K+ managed inboxes, 3,000+ domains, 1,631+ clients, 50M+ emails delivered monthly. Prices exclude domain registration unless a plan states domains are included, at every provider in the table.

Unverified: competitor prices come from our own [alternatives pages](https://maildeck.co/alternative), last checked against each vendor's public pricing in May 2026, and were not re-checked on the vendors' sites on the publication date. The cost-per-1,000-sends figures apply our Premium-tier limit of 8-10 sends per inbox per day to every provider, because none of the four publishes a per-inbox daily limit for its Outlook product; if a vendor publishes its own figure, use theirs. Where a vendor quotes a price range, both ends are shown. Providers whose Outlook product we could not confirm are not in the table: [Mailscale](https://maildeck.co/alternative/mailscale), [Winnr](https://maildeck.co/alternative/winnr), [Maildoso](https://maildeck.co/alternative/maildoso), [Mailforge](https://maildeck.co/alternative/mailforge), [Infraforge](https://maildeck.co/alternative/infraforge) and [Aerosend](https://maildeck.co/alternative/aerosend) sell SMTP rather than Microsoft inboxes.

Last updated: October 2026

Written by [Nikita Stoletov](https://maildeck.co/authors/nikita-stoletov)

CTO | Outbound Infrastructure & Deliverability Engineering

Built the infrastructure delivering 50M+ emails monthly across 3,000+ domains with 98% inbox placement at MailDeck.

[LinkedIn](https://www.linkedin.com/in/nikita-stoletov-30b817292)

[View Profile](https://maildeck.co/authors/nikita-stoletov)

## Ready to Scale Your Email Infrastructure?

Join top outbound teams using MailDeck for enterprise-grade deliverability.

[Get Started](https://app.maildeck.co)

## Continue Reading

[Guide](https://maildeck.co/blog/microsoft-365-vs-google-workspace-cold-email)

### [Microsoft 365 vs Google Workspace for Cold Email: Deliverability Benchmark 2026](https://maildeck.co/blog/microsoft-365-vs-google-workspace-cold-email)

[Which inbox type actually lands, measured across both official provider IP pools at volume.](https://maildeck.co/blog/microsoft-365-vs-google-workspace-cold-email)

[Guide](https://maildeck.co/blog/cold-email-inbox-provider-how-to-choose)

### [Cold Email Inbox Provider: How to Choose the Right One for Your Use Case](https://maildeck.co/blog/cold-email-inbox-provider-how-to-choose)

[The questions to ask before buying inboxes, and which provider type fits which sending profile.](https://maildeck.co/blog/cold-email-inbox-provider-how-to-choose)

[Comparison](https://maildeck.co/blog/cheap-cold-email-inboxes-pricing-by-provider)

### [Cheapest Cold Email Inboxes in 2026: 5 Providers Compared at Every Scale](https://maildeck.co/blog/cheap-cold-email-inboxes-pricing-by-provider)

[Per-inbox pricing across providers at 100, 500 and 1,000 inboxes, with the hidden costs that move the total.](https://maildeck.co/blog/cheap-cold-email-inboxes-pricing-by-provider)