---
title: "📋FTAPI Gateway: Configuring O365 Send and Receive Connectors"
url: "https://support.ftapi.com/en/article/einrichtung-von-o365-sende-und-empfangsconnectoren"
language: "en"
last_updated: "2026-06-22T07:10:52.249Z"
---

# 📋FTAPI Gateway: Configuring O365 Send and Receive Connectors

This article describes how to configure the necessary connectors for inbound and outbound email traffic, as well as the required transport rules and TLS policies for the FTAPI S/MIME Gateway in the Exchange Admin Center.

## Adding an inbound O365 connector

To forward emails from the gateway to O365, add a new mail flow connector:

1.  Log in to the **Exchange Admin Center**.
2.  Under **Mail flow** -> **Connectors** -> **Add a connector**, create a new connector.
3.  In the "From" field, select: **Your organization's email server**.
4.  In the "To" field, select: **Office 365**. Click **Next**.
5.  Enter a name (e.g., `FTAPI S/MIME Inbound Connector`) and an optional description.
6.  Under "What should happen after the connector is saved?", select **Turn it on** and **Retain internal Exchange email headers**.
7.  Click **Next**.
8.  Under "How should Office 365 identify email from your email server?", select **By verifying that the subject name on the certificate...** and enter the domain name of the gateway's TLS certificate.
9.  Click **Create connector**.

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## Adding an outbound O365 connector

To forward emails from O365 to the FTAPI gateway, add a new mail flow connector:

1.  Log in to the **Exchange Admin Center**.
2.  Under **Mail flow** -> **Connectors** -> **Add a connector**, create a new connector.
3.  In the "From" field, select: **Office 365**.
4.  In the "To" field, select: **Your organization's email server**. Click **Next**.
5.  Enter a name (e.g., `FTAPI S/MIME Outbound Connector`) and an optional description.
6.  Under "What should happen after the connector is saved?", select **Turn it on** and **Retain internal Exchange email headers**.
7.  Click **Next**.
8.  Select **Only when I have a transport rule set up that redirects messages to this connector**. Click **Next**.
9.  Add a new smart host by clicking the **+** icon.
10.  Enter the fully qualified domain name (FQDN) of the FTAPI gateway (e.g., `ftapi-smime.example.com`).
11.  Click **Save** and then **Next**.
12.  Ensure that **Always use Transport Layer Security (TLS) to secure the connection** and **Issued by a trusted certificate authority (CA)** are selected. For additional security, you can optionally enable domain name validation. Click **Next**.
13.  In the next step, the connector is validated by sending an email from Office 365 through the connector. Enter a valid email address to receive a test email and click **Validate**.
14.  After successful validation, click **Save**.

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## Configuring forced TLS

To ensure that the connection from the FTAPI gateway to O365 is secured using TLS, proceed as follows:

1.  Open the MTA assignments page: **MTA** -> **Maps**.
2.  Click **tls-policy**.
3.  Add the following line: `[<your-o365-domain>.mail.protection.outlook.com]:25 verify match=mail.protection.outlook.com`
4.  Click **Save**.

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## Creating and assigning transport rules

### Inbound

Create a new rule via **Add a rule**:

-   **Name:** e.g., `S/MIME inbound`
-   **Apply this rule if:**
    -   The sender is: **external/internal** -> **Outside this Organisation**
    -   AND
    -   The recipient is: **external/internal** -> **Inside this Organisation**
-   **Do the following:**
    -   Redirect the message to -> the following connector -> **FTAPI S/MIME Inbound Connector**
-   **Except if:**
    -   The message headers include any of these words:
        -   Header name: `Received`
        -   Words: `<FQDN of the FTAPI S/MIME server>`

* * *

### Outbound

Create a new rule via **Add a rule**:

-   **Name:** e.g., `S/MIME outbound`
-   **Apply this rule if:**
    -   The sender is: **external/internal** -> **Inside this Organisation**
    -   AND
    -   The recipient is: **external/internal** -> **Outside this Organisation**
-   **Do the following:**
    -   Redirect the message to -> the following connector -> **FTAPI S/MIME Outbound Connector**
-   **Except if:**
    -   The message headers include any of these words:
        -   Header name: `Received`
        -   Words: `<FQDN of the FTAPI server>`