Google Workspace if most of your recipients are at Gmail and you want the simplest provisioning. Microsoft 365 if your recipients are corporate Outlook users, or if you want tenant boundaries that contain damage at about twenty-five users each. Neither is categorically better, and fleets above a hundred mailboxes usually end up mixed, which is also the most resilient answer because a problem at one provider does not stop the other.
Read on 19 September 2026 from each provider's published limits. emailcampaign.ai provisions both, so this page has no reason to prefer one.
Side by side on the things that decide it
| Google Workspace | Microsoft 365 | |
|---|---|---|
| Published daily limit | 2,000 messages a day, 500 on a trial | 10,000 recipients a day, 30 messages a minute |
| External recipients | 3,000 a day | 500 recipients per message |
| Users per tenant for cold email | No practical tenant boundary | About 25 on a fresh tenant |
| DKIM setup | Generated in the Admin console, then start authentication | Two CNAMEs with a per-tenant target that must be read, not guessed |
| Best for | Gmail recipients, simplest provisioning | Corporate Outlook recipients, contained damage |
| Reputation visibility | Google Postmaster Tools, free | Little published |
Where Google wins
Placement at Gmail, which is where most business replies come from. Provisioning is simpler, particularly through domain-wide delegation, and DKIM is generated in the Admin console in a couple of clicks. Google also publishes the one reputation number you get told directly: keep the spam complaint rate under 0.1 percent and never at 0.3 percent, visible for free in Google Postmaster Tools.
The published sending limits are two thousand messages a day on a paid account, five hundred on a trial, and three thousand external recipients a day. You will never approach these sending eight to ten a day per mailbox, which is the point.
Where Microsoft wins
Reaching corporate Outlook recipients, where Microsoft's own infrastructure is the receiving side. Tenants give you a real boundary: about twenty-five licensed users on a fresh tenant, eight domains in a batch, three to four users per domain, and damage that stays inside the tenant.
Exchange Online's limits are ten thousand recipients a day, thirty messages a minute, and five hundred recipients per message. Again, abuse ceilings rather than guidance.
One warning that costs people weeks: the DKIM CNAME target inside your tenant's onmicrosoft.com domain contains a per-tenant value. A record copied from a guide or from a tenant you set up last month resolves to nothing, and DKIM quietly never signs. Read the exact target from the tenant you are configuring.
What about self-hosting
A third route: your own mail hosts, your own DKIM keys, your own IP addresses. It costs the least per mailbox at scale and gives the most control, including control over reputation you cannot borrow. The price is that you operate it, and that work never stops: IP warm-up, blocklist monitoring, patching, reverse DNS, certificates. It suits fleets large enough that per-seat costs dominate and teams with someone to run it.
The cost comparison people actually want
| Route | Seats | Domains | Note |
|---|---|---|---|
| Google Workspace | $8.40 a seat, so about $840 | 50 domains, about $50 a month spread over the year | Plus a one-off setup per mailbox |
| Microsoft 365 | Microsoft's rate for the plan you pick | Same | Four tenants at about 25 users each |
| Self-hosted | From $39 a month per server, three for $99 | Same | Marginal mailbox cost is near zero; operations are not |
Questions, answered straight
- Do I need separate domains either way?
- Yes. Never send cold email from the domain your company runs on, whichever provider you choose. Reputation damage follows your invoices, password resets and support replies.
- Can I mix both in one campaign?
- Yes, and above about a hundred mailboxes most serious senders do. It spreads provider risk and lets you match the sending provider to the recipient's provider.
- Which is cheaper?
- Google's seat price is published and predictable. Microsoft's depends on the plan. Self-hosting is cheapest per mailbox and most expensive in hours, which is the column most comparisons leave out.
- Does Google ban accounts for cold email?
- Google suspends accounts for abuse signals: complaint rates, sudden volume, bounce patterns. Sending eight to ten a day from a warmed mailbox to a verified list is nowhere near that line.
Published 19 September 2026. Updated 19 September 2026. Written by the team that runs the infrastructure; numbers come from the platform's own provisioning and sending, and from the providers' published documentation at the time of writing.