How to Set Up a Mail Flow Rule for External Email Messages

How to Set Up a Mail Flow Rule for External Email Messages

You’re trying to set up a mail flow rule that will include a disclaimer to help protect members of your organization against harmful elements from external email messages from non-organization addresses.

Unfortunately, after setting up a rule, putting up a nice code to make the disclaimer pop out, you find out that the rule doesn’t work. Even the colors you set up didn’t work as expected (or worse, didn’t show at all!).

In this article, let’s address this issue. I’ll also show you step-by-step instructions on what to do to set up a working mail flow rule for external email messages.

How to Set Up a Mail Flow Rule for Non-Organization Addresses

Here are the steps you need to take:

Step 1: Create a Rule in Exchange Admin Center

The first step you need to take is to access the Exchange Admin Center. Simply click on the previous to directly visit the page or you can also land on any admin centers and go to Exchange from there.

Once you’re there, all you need to do is go to Mail flow > Rules.

To create a rule, click on the plus icon and select “Create a new rule”.

To create a new rule, visit the Exchange Admin Center, open the mail flow tab, and select the rules option.

Step 2: Name the Rule

After following the earlier steps, a new window will open up where you can customize the new rule.

To start with, name your rule with something that will make sense to you even after creating hundreds of rules.

For this example, we’re naming the rule:

External Messages From Non-Organization Addresses

Step 3: Specify What the Rule Will Do

The next step is to specify the conditions for when the rule with be applied.

For this, you need to set the application of the rule to the following:

  • The sender is located outside the organization.
  • The recipient is located inside the organization.

By default, you can only add one condition. To add another one, you must click the “More options” link below the window.

You can find it at the bottom of the new window that popped out.

It should look like this. Note that if you’re having trouble with how to set it up, simply follow the options selected shown on the image below.

Set the sender to be located outside the organization while the recipient should be inside the organization.

Step 4: Prepend a Disclaimer

After specifying the conditions, you will then have to define what the rule will do.

For this, select the “Prepend a disclaimer” option.

Again, it may be confusing for you since that option is a second-level one. Hover your mouse over the “Apply a disclaimer to the message” and select the right option.

To select the prepend the disclaimer option, you must first hover your mouse over the apply a disclaimer to the message option.

Step 5: Enter the Code

The next step is where you can enter the code that will make the disclaimer pop out.

To do so, click on the “Enter text” link on the right side of the option you set up earlier.

You can find the "Enter text" link beside the option where you selected the prepend the disclaimer option.

Then, copy the following code to the window that popped up (where you can write the code).

<p><div style="background-color:#FFEB9C; width:100%; border-style: solid; border-color:#9C6500; border-width:1pt; padding:2pt; font-size:10pt; line-height:12pt; font-family:'Calibri'; color:Black; text-align: left;"><span style="color:#9C6500"; font-weight:bold;>CAUTION:</span> This email came from someone outside of the organization. Do not click the links or open any attachments unless you recognize the sender and know the content is safe.</div><br></p>

It should then look like this:

A high-level view on the steps you need to take to create a mail flow rule for external email messages.

Once you’re done, click on the “Save” button.

That’s it! You now have a working mail flow rule that will put up a disclaimer for all emails coming from outside your organization sent to anyone in your organization.

If you have any other questions, feel free to drop them down below in the comments section. If you want to reach me directly, you can send me a personal message on the contact page.

About Ryan Clark

As the Principal Solutions Architect at Mr. SharePoint, I help companies of all sizes better leverage Modern Workplace and Digital Process Automation investments. I am also a Microsoft Most Valued Professional (MVP) for Office Apps & Services.

Notify of
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x
Scroll to Top