Cheapest Microsoft 365 & Outlook inboxes for cold email (October 2026)
Microsoft mailboxes are the main alternative to Google for cold email, and pricing is all over the place: per-inbox, per-tenant and flat "unlimited" plans. For 30 inboxes on 10 domains, Microsoft options run $11.37 to $158.72/mo. The cheapest, Puzzle Inbox (Outlook 365 inboxes (3 sends/day each)), comes with a tight sending cap (3 emails per inbox per day), so check volume before you buy.
Last updated 2026-10-23 · 8 offerings · list prices, monthly billing
Verdict by use case
$11.37/mo; 3 emails per inbox per day.
Price comparison
| Platform | + 10 domains | Minimum | Warmup | Link | ||||
|---|---|---|---|---|---|---|---|---|
| Microsoft | $0.35 | $10.50 | $0.87 * | $11.37 | None stated | Optional | View pricing | |
| GoogleMicrosoft | $3.00 | $90 | $8.72 * | $98.72 | None | Add-on | View pricing | |
Zapmail Google & Microsoft mailboxes |
GoogleMicrosoft | $3.30 † | $99 | $8.72 * | $107.72 | 10 mailboxes (starter plan, third-party) | Optional | View pricing |
Cheap Inboxes Google & Microsoft mailboxes |
GoogleMicrosoft | $3.50 | $105 | $8.33 | $113.33 | None stated | Unclear | View pricing |
Premium Inboxes Google & Microsoft mailboxes, done-for-you |
GoogleMicrosoft | $3.50 | $105 | $8.72 * | $113.72 | No monthly commitment | No | View pricing |
Primeforge Google Workspace & Microsoft 365 mailboxes |
GoogleMicrosoft | $4.50 | $135 | $11.67 | $146.67 | 10 mailbox slots | No | View pricing |
Inframail Microsoft-backed inboxes, flat fee |
Microsoft | Flat plan † | $147 | $8.72 * | $155.72 | Flat plan | No | View pricing |
Mailpool Microsoft 365 inboxes |
Microsoft | $5.00 | $150 | $8.72 * | $158.72 | None stated | Unknown | View pricing |
Total = list price for 30 mailboxes on the cheapest plan that fits + 10 sending domains amortised monthly. * Domain price unknown or bring-your-own: reference .com at $10.46/yr. † Price from a third-party comparison. € rows are in euros excl. VAT and are excluded from "cheapest" badges. Monthly billing, list prices, checked 2026-10-23.
Frequently asked questions
What is the cheapest Microsoft 365 inbox for cold email?
Puzzle Inbox (Outlook 365 inboxes (3 sends/day each)) at $11.37/mo for 30 mailboxes incl. domains, but with a cap of 3 emails per inbox per day. Without a published cap, InboxKit at $98.72/mo.
Are Outlook inboxes good for cold email?
Many senders mix Microsoft and Google inboxes to reach both kinds of recipients. MailboxWatch compares price and plan terms only; we don't test deliverability.
What is a flat-rate Microsoft inbox plan?
Some providers (e.g. Inframail) charge one monthly fee for unlimited inboxes. It's poor value at small volume and very cheap per inbox at large volume.