> ## 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.

# Introduction

> TenantCore is the engine that builds and manages Microsoft 365 infrastructure for cold email. Tenants, domains, mailboxes, and send limits, all in one place.

## What is TenantCore?

TenantCore provisions and manages Microsoft 365 sending infrastructure for cold email operators, outbound agencies, and lead generation teams.

Instead of manually setting up tenants, attaching domains, adding mailboxes and roles, and configuring Exchange. TenantCore handles the infrastructure layer end to end. You connect a Microsoft 365 tenant, add your domains, and TenantCore does everything else.

## Who it's for

TenantCore is built for operators who already understand cold email infrastructure and want a more reliable way to manage it:

* **Solo operators** running multiple domains across multiple clients
* **Cold email agencies** managing tenant infrastructure for a book of clients
* **Lead gen teams** who need consistent, scalable sending infrastructure without manual overhead

If you're running more than a handful of mailboxes and managing infrastructure by hand, TenantCore is the missing layer.

## How it works

TenantCore sits between Microsoft 365 and your sending tool. It provisions the infrastructure, enforces the limits, and keeps everything organized in one place.

```plaintext theme={null}
Microsoft 365 tenant
  └── TenantCore
        ├── Domain management (up to 12 per tenant)
        ├── Mailbox provisioning (up to 3 per domain)
        ├── Send limit enforcement (Exchange transport rules)
        └── Your sending tool (Smartlead, Instantly, etc.)
```

Send limits are enforced at the Exchange Online transport rule level. That means the ceiling is held by Microsoft's infrastructure, regardless of how your sending tool is configured.

## Where to start

<CardGroup cols={2}>
  <Card title="Overview" icon="map" href="/getting-started/overview">
    Understand the infrastructure model before you build
  </Card>

  <Card title="Prerequisites" icon="list-check" href="/getting-started/prerequisites">
    What you need before connecting your first tenant
  </Card>

  <Card title="Quickstart" icon="bolt" href="/getting-started/quickstart">
    Provisioned and sending in under 10 minutes
  </Card>

  <Card title="API Reference" icon="code" href="/api-reference/introduction">
    Automate provisioning with the TenantCore API
  </Card>
</CardGroup>