Configuring Outbound Filtering with Office 365 (Exchange Online)

Before you start

  • Make sure Outbound Filtering is configured. You need to make sure that you have received the SMTP Relay and SMTP change instructions from our team. 
  • Check your SPF record. If your domain has no SPF record, no need to worry. However, if any of your domains have an SPF record, it absolutely needs editing. Make sure to add the following entry in your SPF records: a:outbound.zerospam.ca

Please note: with this configuration active, your bounce messages will not show up in our communication logs. They will be relayed by your portal domain (domain.onmicrosoft.com) and will show up in your Office 365 Message Traces.

Set up a Connector in Office 365

1
Access your Exchange Online Admin Center.
2
Click on Mail Flow, then Connectors and add a new connector by clicking on the + button.

3

Select your mail flow scenario to be:

From: Office 365
To: Partner Organization

4
Give your connector a descriptive name so that you can easily recognize it's purpose later.

(e.g. Outbound Filtering Connector)

5
Select " Only when I have a transport rule set up that redirects messages to this connector when asked when this connector should apply.

6
When asked to choose how to you want to route email messages, select " Route messages through these smart hosts, click on +, and enter your SMTP Relay.
7
The options " Always use Transport Layer Security (TLS)" and " Issued by a trusted certificate authority (CA)" can remain selected.
8
Review your settings and click Next to validate the connector. Do this by adding a test recipient on a domain external to your organization and click the Validate button.

The test is done in two parts: it checks that the connector is valid and that an email can be sent. The first part of the test should pass and the second should fail. The second test will always fail because the test email uses an empty mail-from. This will be rejected by our filters.

As long as the first test (Connector Validation) passes, everything is alright.

9
Once Connector Validation passes, click Save to finish.

Create a Mail Flow Rule in Office 365

1
Access your Exchange Online Admin Center.
2

Click on Mail Flow, then Rules, and add a new mail flow rule by clicking on the + button.

3

Give your mail flow rule a descriptive name so that you can easily recognize it's purpose later
( e.g. Route to outbound filtering).

4
Before continuing, click on More options... lower on the page to reveal the options you'll need to use.
5

Set the rule to apply when the sender domain is any of your filtered domains.

*Apply this rule if...
"The sender..." → "domain is..."

Make sure to include any and all domains you have filtered with us.

6

Set the rule to redirect to the connector you created earlier.

*Do the following...
"Redirect the message to..." → "the following connector..."
7

Set exceptions to this rule for automatic replies and messages meant for your own domains.

Except if...
"The recipient..." → "domain is..."
"The message properties..." → "include the message type..."

8
Save the rule.