> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tenantcore.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Microsoft Sending Limits

> Advanced context on Microsoft tenant-level sending limits and how they relate to TenantCore mailbox controls.

# Microsoft Sending Limits

Microsoft applies its own service limits and anti-abuse controls to Exchange Online.

These limits exist independently of TenantCore.

TenantCore's mailbox sending controls are designed to operate comfortably below the point where an operator should be treating Microsoft's tenant-wide limits as normal campaign capacity.

## TenantCore's normal operating model

TenantCore is designed around:

```text theme={null}
25 sends/day per mailbox
×
36 mailboxes per tenant
=
up to 900 sends/day per tenant
```

That is a TenantCore operating limit, not a claim that Microsoft guarantees delivery at that volume.

## Microsoft tenant-level limits

Microsoft can apply tenant-level recipient and sending limits based on factors such as:

* tenant licence composition
* tenant age and history
* service protections
* abuse signals
* Microsoft policy changes

Microsoft can change its limits or enforcement behavior independently of TenantCore.

## Why TenantCore does not treat Microsoft's maximum as a target

A platform limit is not the same thing as a healthy outbound operating target.

If Microsoft permits a tenant to send more mail, that does not mean an operator should automatically increase mailbox volume to that number.

TenantCore uses lower mailbox-level controls because they are easier to reason about operationally and because reputation risk depends on recipient response, not just Microsoft's published service ceiling.

## TERRL and similar Microsoft limits

Microsoft has used tenant-level recipient limits such as TERRL as part of Exchange Online's service-protection model.

These limits should be treated as Microsoft service constraints, not as TenantCore campaign recommendations.

TenantCore's infrastructure design should continue to work from its own mailbox and reputation controls rather than assuming that a Microsoft tenant-level limit is stable, permanent, or an appropriate sending goal.

## Reputation still matters

Even if a tenant is far below a Microsoft service limit, poor sending behavior can still result in:

* filtering
* hard bounces
* restricted users
* outbound spam controls
* other Microsoft anti-abuse actions

See [Monitoring & Reputation](./monitoring-reputation) for the signals TenantCore uses to help surface those issues.

## Advanced reference

This page is intentionally background context.

For normal TenantCore operation, use:

* [Send Limits](./send-limits) for TenantCore mailbox controls
* [DNS & Domain Readiness](./dns-setup) for authentication setup
* [Monitoring & Reputation](./monitoring-reputation) for reputation state
* [Reports](./reports) for historical operational data