---
title: "Introduction"
manual: "Microsoft Exchange 365 Mailer"
version: "main"
permalink: "https://docs.typo3.org/permalink/oliverkroener/ok-exchange365-mailer:introduction@main"
source: "Introduction/Index.rst"
rendered: "2026-10-04T20:03:13+00:00"
---

# Introduction {#introduction}

## What does it do? {#what-does-it-do}

The **Microsoft Exchange 365 Mailer** extension replaces TYPO3's default SMTP
mail transport with a custom transport that sends emails via the
[Microsoft Graph API](https://learn.microsoft.com/en-us/graph/api/user-sendmail).

Instead of configuring an SMTP server, you register an application in
**Microsoft Entra ID** (formerly Azure AD) and authenticate using the
**OAuth 2.0 client credentials flow** — no user interaction or stored
passwords required.

## Features {#features}

-   Send emails through Microsoft Graph API — no SMTP required
-   OAuth 2.0 client credentials flow for server-to-server authentication
-   Supports backend (environment variables / TYPO3 settings) and frontend
    configuration, the latter via a TYPO3 13/14 [site set](https://docs.typo3.org/permalink/oliverkroener/ok-exchange365-mailer:sitesets@main) or
    the classic TypoScript static template
-   Credentials can be read from the environment in TypoScript with
    `:= getEnv(...)` — see [Recommended: read the credentials from the environment](https://docs.typo3.org/permalink/oliverkroener/ok-exchange365-mailer:frontend-getenv@main)
-   Compatible with Powermail, TYPO3 Form Framework, and other form
    extensions
-   Optional saving of sent emails to the sender's "Sent Items" folder
-   Automatic credential blinding in TYPO3's configuration module, for
    `TYPO3_CONF_VARS` and site settings
-   One OAuth token per request, short timeouts (10 s connect / 30 s total)
    and no duplicate sends on a stalled connection — see
    [Graph client, timeouts and retries](https://docs.typo3.org/permalink/oliverkroener/ok-exchange365-mailer:architecture-graph-client@main)
-   Tested on every supported TYPO3 version with real Microsoft Graph sends —
    see [Testing](https://docs.typo3.org/permalink/oliverkroener/ok-exchange365-mailer:testing@main)
-   Works with shared mailboxes and Application Access Policies
-   **Send As / Send On Behalf** via the optional `graphSenderUserId`
    setting — decouples the Graph mailbox used for the API call from the
    visible `From` header so a configured mailbox can send on behalf of
    another

## Requirements {#requirements}

-   **TYPO3**: 12.4 LTS, 13.4 LTS, or 14.x
-   **PHP**: 8.1 – 8.5
-   **Dependencies**:

    -   `microsoft/microsoft-graph` ^2 — Microsoft Graph SDK
    -   `oliverkroener/ok-typo3-helper` ^3 — provides `MSGraphMailApiService`
        for message conversion