Warm up your Microsoft 365 mailboxes with MailPilot
MailPilot warms up Microsoft 365 (Office 365) business mailboxes with Microsoft OAuth and modern authentication — the same standard Microsoft now mandates for tenant mailboxes. You connect each user through the consent screen, and MailPilot sends and reads via the Graph API on your custom domain. Like Google Workspace, Microsoft 365 reputation is domain-scoped and routed through Exchange Online's shared outbound pools, so building consistent, well-authenticated sending history across your domain is what keeps cold outreach out of Junk.
How it works with Microsoft 365
Connect via modern auth
Sign in with Microsoft OAuth for each Microsoft 365 user. Basic auth is disabled on most tenants, so MailPilot uses modern authentication through the Graph API.
Lock down domain authentication
Verify SPF, DKIM, and DMARC for your Microsoft 365 domain. Exchange Online signs your mail, and receivers check those records on every message — MailPilot flags any gaps.
Warm the domain in parallel
MailPilot ramps all connected 365 mailboxes together to build consistent domain-level history across Exchange Online's shared sending infrastructure.
Track placement per user
Monitor inbox vs. Junk for every mailbox and a domain-wide outreach-ready status before launching campaigns.
Why warm up Microsoft 365
Microsoft 365 routes outbound mail through Exchange Online's shared pools, so your domain's reputation — not a dedicated IP — is what determines placement. Warmup builds that domain trust.
Fresh 365 tenants and newly added users have no sending history; Microsoft's filters treat them cautiously until warmup establishes a pattern of wanted mail.
DKIM is not enabled by default on many 365 domains. MailPilot verifies DKIM, SPF, and DMARC so your warmup traffic is fully authenticated from day one.
Microsoft 365 warmup FAQ
Is Microsoft 365 warmup different from Outlook.com warmup? +
The auth method is the same (Microsoft OAuth), but Microsoft 365 mailboxes send from your business domain through Exchange Online, so warmup builds custom-domain reputation. Outlook.com/Hotmail are consumer addresses on Microsoft's own domain.
Does my tenant admin need to enable anything? +
The OAuth connection works with standard user consent. The main requirement is domain authentication — many 365 domains ship without DKIM enabled, so use MailPilot's DNS checker to confirm SPF, DKIM, and DMARC are all valid.
Can I warm up an entire team of 365 mailboxes? +
Yes. Because reputation is domain-scoped, warming multiple users in parallel builds stronger, more consistent domain history. The Growth plan supports up to 30 mailboxes and Scale is unlimited.
Warm up Microsoft 365 the right way
Free plan available. 14-day trial on paid plans, from $9/mo. No credit card. Connect your Microsoft 365 mailbox in minutes.
Get started free →