Removing the External Warning Banner for Exchange 2013, 2016, or Microsoft 365

Your mail client may automatically place a warning banner on emails that come from a sender who is outside of your organization. When this banner displays, it may affect the way your user interacts with the phishing test and may cause inaccurate phishing test results. This guide will show you how to remove these warnings from KnowBe4 phishing emails.

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How to Remove the Warning Banners in Your Organization

How to Remove the Warning Banner With HTML

How to Remove the Warning Banner in Exchange 2013, 2016, or Microsoft 365

To remove external warning banners from emails that are received by your users, you will need to whitelist KnowBe4 in your mail client. Please see our Whitelisting Data and Anti-Spam Filtering Information article for more information.

1. Navigate to your Exchange or Microsoft 365 account.
2. Log into your mail server admin portal and click Admin.
3. Click Exchange under Admin Centers in the left-hand menu.
4. From the Exchange admin center, select Mail Flow from the left-hand menu.
5. Click the last KnowBe4 mail rule in your priority list and then click the pencil icon beneath Rules.

6. Click More options.
7. Select the checkbox followed by the text Stop processing more rules.
8. Click Save.
9. Click on the mail rule used to add external warning banners in your organization. The name of this rule may vary depending on your organization’s mail rules.
10. Using the arrow icons beneath Rules, move the priority of your warning banner mail rule beneath KnowBe4’s whitelisting mail rules.

How to Remove the Warning Banner With HTML

You can remove the warning banners by adding CSS to the HTML’s header tag. By using this method, you can hide the warning message while maintaining the body of the email. However, users may still see the external warning banner when previewing the email in some mail clients. This implementation will also need to be used on every KnowBe4 phishing template, which may be time consuming.

For more information about how you can use HTML styling to hide banners in your own mail client, see WhyNotSecurity’s MS External Email Warning Bypass article.

Any mail rules beneath KnowBe4’s whitelisting rule in the mail rules hierarchy will no longer be processed and external warning banners will not be added to your emails. For further assistance with this bypass, please contact our support team and they will be happy to help.