How do I configure Office365 to prevent incoming messages from being blocked?

To avoid incoming messages being blocked by Office365's spam filter, you should whitelist the IPs we use to deliver messages to your mail server. To do this, please proceed as follows:

Authorization based on the IP address of the delivery server

1

Log in to the Exchange Admin Center.

2

Click on Mailflow and then on Connectors.

3

Click the plus sign (+).

4

Select "Partner organization" for "From" and "Office365" for "To".

5

Select "Use the sender's IP adress" and click "Next".

6

Add the IP addresses from our website. Since the IP addresses can change, I recommend that you subscribe to the newsletter. You will then automatically be informed by e-mail about changes to the pool.

7

Make sure in the following window that the option "Reject email messages if they aren't over sent over TLS" is selected and click on "Next".

8

Check the settings and click "Save".

9

Go to Mail flow> Rules.

10

In the "Rules" tab, click on the plus sign (+) and select "Bypass spam filtering".

11

Enter a name for the rule.

12

Select "Apply this rule if..." and then "Senders IP Address is in any of these ranges or exactly matches".

13

Add the IP addresses from our website.

14

Make sure that the setting "Do the following..." is set to "Modify the message properties > Set the spam confidence level (SCL) > Bypass spam filtering".

15

Click on "Ok" and then on "Save".

Authorization based on a rule that searches the header

This disables Office365's spam filtering, preventing Office365 from incorrectly marking legitimate messages delivered by EuropeanMX as spam (e.g., because SPF checking fails). Due to the fact that you are using EuropeanMX for spam checking, Office365 filtering is no longer required.

The drawback of this method is that spammers can technically fake the message header, which makes the subsequent method impossible. The advantage of this method is that you no longer need to capture and add IP addresses, which can change constantly.

1

Log in to the Exchange Admin Center.

2

Select the item "Rules" under "Mail Flow".

3

Click the plus sign (+) under "Rules" and create a new rule.

4

Enter a name for the rule, e.g. "EuropeanMX spam filter bypass".

5

Select the option "More options".

6

Create the following rule:

A message header includes"X-Recommended-Action" header includes >> contains "accept"

7

Click on the plus sign (+) and select "Ok".

8

Go to "Do the following" and select "Modify the message properties" > "Set the spam confidence level (SCL)" > "Specify SCRL" > "Bypass spam filtering".

9

Click on "Ok" to complete the settings.