Business email
Microsoft 365 sending limits
Microsoft 365 (Exchange Online, paid)
| Account / daily limit | 10,000 recipients per day per user mailbox. Separately, a tenant-wide External Recipient Rate Limit (TERRL), rolled out from April 2025 and scaled by paid-license count, caps total external recipients per 24h across the tenant. |
|---|---|
| Send rate | 30 messages per minute per user. |
| Recipients per email | 500 recipients per message by default; an admin can raise it to a maximum of 1,000 (Set-Mailbox -RecipientLimits). It cannot go above 1,000. |
The account cap is not a cold-email volume
The 10,000/day per-user figure is an anti-abuse guardrail, not a cold-send allowance. Inbox-safe cold volume per warmed mailbox is ~30-50/day (start 5-10/day and ramp 2-4 weeks) -- roughly 200x below the per-user cap. The April-2025 TERRL is a hard org-wide ceiling on external mail that can throttle a whole tenant independent of per-mailbox limits.
Good to know
- Per-user daily limit is a rolling 24h window (e.g. 5k at 9am + 2.5k + 2.5k = locked until 9am next day).
- The 500-per-message default trips up bulk senders constantly; raising to 1,000 requires explicit admin action.
- TERRL is license-count-based and shared across all senders in the tenant -- model it separately from the per-user cap.
Scale safely past one inbox.
Real cold-email scale comes from many inboxes each sending a safe volume, not one inbox maxing its cap. Scheduler Zero spreads sending across warmed inboxes and paces it for you.