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Real Outlook business accounts on prewarmed .com domains, DNS human-verified, delivered within 48 to 72 hours and sending on arrival. The matching infrastructure for the enterprise half of your lead list that lives on Microsoft.
The same infrastructure behind 1,000,000+ cold emails every month at 4%+ reply rates.
Built by operators for their own agency first, sold to you second.
Enterprise B2B runs on Microsoft. Finance, insurance, manufacturing, legal, healthcare: the buyers with budgets are overwhelmingly behind Outlook and Exchange Online, and Microsoft filters strangers hard.
Run any enterprise-heavy list through our free ESP Segmenter and watch the Microsoft share. In our own campaigns, sending to Outlook-hosted prospects from matching Microsoft infrastructure meets less filtering friction than sending to them from elsewhere.
Outlook’s SCL scoring junks new, unknown senders faster than any other filter, which makes warmed history worth more on Microsoft than anywhere. A prewarmed M365 inbox arrives already familiar, the single biggest head start you can buy on this platform.
Tenant setup, Exchange Online configuration, authenticated SMTP or OAuth, connectors, and DNS records that break silently: Microsoft setup is where DIY infrastructure projects go to die. We handle all of it and hand-verify every record before your CSV ships.
Cheap MS365 resellers stack customers into shared tenants where one bad sender poisons everyone. Every WarmInboxes customer gets isolated infrastructure, so your reputation is only ever a product of your own sending.
Free prewarmed .com domains with every order save $12 to $20 each before counting warmup time. Bulk tiers cut the per-inbox rate at volume, quarterly and yearly billing cut it again, and fresh inboxes on branded domains run a fraction per send when you scale.
Fresh Microsoft accounts often need the most patient warmup in cold email because SCL filtering distrusts new senders. Prewarmed M365 inboxes carry that history already, so you send the day they land instead of babysitting a ramp for three weeks.
SCL scores, connector limits, throttling policies, the Outlook-specific traps: our team sends 1M+ cold emails a month across Google and Microsoft and supports you on WhatsApp 24/7. When something breaks mid-campaign, an operator works the fix with you.
55 free deliverability tools including an Outlook SCL Analyzer built for exactly this platform, a free B2B leads database of 999 lists, expert playbooks, and 101 guides. The full stack our agency runs on, included.
Most providers hand you inboxes and hope. We give you the operating system we run our own 1M+ sends a month on.
Free .com domains, already warmed. Delivered within 48 to 72 hours and sending the day they land. Plug the CSV into your sequencer and go.
Once the campaign is booking meetings, layer in fresh inboxes at a fraction of the cost per send and let them warm behind live sending.
Domains get flagged, that is the sport. One WhatsApp message gets the cause diagnosed with you, and more prewarmed inboxes ordered if you need them.
We made every internal tool our agency's GTM engineers use public and free. Customers get infrastructure plus the whole operating kit.
Checkers for SPF, DKIM, DMARC, MTA-STS, blacklists, spam copy, CSV cleaning, inbox planning, and more. No account needed.
Browse the toolsDownloadable lead lists by industry and geography, hundreds of thousands of companies, emailed to you free.
Get free leadsExpert deliverability playbooks, 101 guides, and 24/7 WhatsApp support from people who send cold email daily.
Read the playbooksNew to this?
Here is what ordering actually involves.
Launch with prewarmed inboxes on free domains, then scale sending volume with fresh inboxes on your own branded domains.
Skip 21 Day warmup wait. Ready-to-use inboxes with a free prewarmed .COM/.CO domain.
(FREE Prewarmed .COM/.CO)
3 Ready-to-use Microsoft inboxes with a free prewarmed domain - no warmup period required.
Paid quarterly
(FREE Prewarmed .COM/.CO)
3 Ready-to-use Google inboxes with a free prewarmed domain - no warmup period required.
Paid quarterly
(FREE Prewarmed .COM/.CO)
100 inboxes per tenant, free prewarmed domain, no warmup needed. $50 per tenant per month.
Paid quarterly
On a budget? Prewarmed inboxes on lower-cost domain extensions from $4.5/inbox. Message us
Everything you need before you order.
Yes. Every inbox is a genuine, officially licensed Microsoft 365 business account, never cracked, farmed, or resold from grey markets. You get full admin access and ownership, with customers isolated from each other so nobody else’s sending can ever touch your reputation.
Naming only. Office 365 was rebranded Microsoft 365 in 2020, Outlook is the mailbox interface, and MS365/M365 are shorthand. Whichever term you searched, the product is the same: Exchange Online business mailboxes on your sending domains, which is exactly what we deliver prewarmed.
Usually SCL scoring: Microsoft assigns every inbound message a Spam Confidence Level, and unfamiliar senders with thin history score badly even with perfect DNS. Warmed Microsoft-native infrastructure attacks the problem at the root, and our free Outlook SCL Analyzer decodes the headers so you can see exactly why a message was junked.
Yes. Inboxes ship as a CSV pre-formatted for Instantly, Smartlead, EmailBison, ManyReach, Apollo, and any tool supporting IMAP/SMTP or OAuth. Plug in and send the day they land.
Match your list. Segment it by receiving provider first: tech and startup lists skew Google-hosted, enterprise and regulated industries skew Microsoft. Serious volume senders run both and route campaigns by recipient provider, which is why we are the rare provider offering Google, Microsoft 365, and Azure under one roof.
Bulk tiers drop the per-inbox price at 30 and 100 inboxes with further cuts on quarterly and yearly billing. Agencies get per-client isolation, so one client’s campaign can never contaminate another’s infrastructure, and fast deployments keep client pipelines moving when domains burn.
Free prewarmed .com domain with every order. Delivered in 48 to 72 hours, human-verified DNS, built for warm deliverability.
Also available: Google Workspace inboxes · Azure inboxes
Google, Microsoft 365 and Azure inboxes with free prewarmed domains and DNS configured before you log in. Prewarmed inboxes send the day they land; every order is delivered within 48 to 72 hours.
Get Prewarmed & Fresh Inboxes