How do I configure Office365 to send messages through the outgoing filter?

Before you start the setup you need to make sure that our servers are also included in the SPF record of your domain. You can find more information about the SPF record in our FAQ article "What is an SPF record and how must it be designed?".

Step 1: Create an outgoing user in EuropeanMX

1

Log in to the admin panel of EuropeanMX as a domain admin. You can find instructions in our FAQ article "How can I log into the Admin panel (web interface of the filter)?".

2

Select "Outgoing" and then "Manage users".

3

Select the "Authenticating Domain" tab and make sure that the domain name you manage in Exchange Online is specified there.

4

Enter a secure password and then select "Add and configure" from the drop-down menu.

You only need the secure password to complete the configuration. It will not be needed for the later configuration of Microsoft365.

5

In the outgoing user's settings, enable the "Re-authentication allowed:" option and make the desired settings. In our FAQ article "How do I set up an outgoing user?" you can find more information about the settings.

Step 2: Create a Connector in Exchange Online

To set up a third-party cloud spam filtering system in Microsoft365, Microsoft has listed specific instructions in its own documentation. A summary of a possible setup can be found below.

1

Log into the admin center of Microsoft365.

2

Select "Show All" in the navigation menu.

3

Click on "Exchange" to enter the Exchange Administration Center

4

Click on "Mail flow" and select "Connectors".

5

Then click "+ Add a connector" and set the following setting:

Set the connection from: Office365
Set the connection to: Partner organization

6

Click on "Next".

7

Assign a name for the connector (e.g. EuropeanMX Outgoing filter) and click "Next".

8

On the Use of Connector window, select "Only when I have a transport rule set up that redirects messages to this connector" and click "Next".

9

Click the plus sign (+) and then click Next.

10

Ensure that the option "Always use Transport Layer Security (TLS) to secure the connection (recommended)" is activated in the "Security Restrictions" tab.

Use "Issued by a trusted certificate authority (CA)".
Then click "Next".

11

Enter a valid email address in the "Validation email" field.

12

Click the plus sign (+) and then click Validate.

13

Once the email has been validated, click "Next".

14

Check the details of the connector again and then select "Create connector".

Step 3: Create a transport rule in Exchange Online

The instructions below are just an example of how you can create the transport rule. Please make your own settings if you need them.

1

Log in to the Microsoft365 Administration Center.

2

Navigate to the Exchange Administration Center in the left menu.

3

Select "Mail flow" and then "Rules".

4

Add a new rule via the plus sign (+).

5

Click on "More options" at the bottom of the window.

6

Assign a name for this rule (e.g. EuropeanMX outgoing).

7

Fill in the fields as follows:

"Apply this rule if the sender's domain is IHREDOMAIN.TLD".
Specify your domain(s) in the popup and click the plus sign (+) if necessary to add each one.
"Do the following: Redirect messages to the following connector"
In the popup dropdown menu, select the connector you created in the 2nd step.
"Except if: The recipient is internal/external"
Select "inside the organization" from the popup.
"Choose a mode for this rule: Enforce".

8

Click "Save" to save the rule.

Once set up, any traffic that matches your outgoing sender domain should be routed through the transport rule and processed by the filter servers.