Disable existing Microsoft Outlook signatures using a Group Policy (GPO)

Overview

You configured the Opensense email signature for Office 365, but some team members still have their previous Microsoft Outlook signatures applied. You can remove Outlook signatures from individual users. To disable them for all users, so that old signatures are not added to future emails, use a Group Policy Object (GPO).

Before you start

• Group Policy
• Devices that are domain-joined (on-premises), with users signed in with their domain user account

Steps at a glance

1. Download and extract the Office Administrative Template for the Outlook version your company uses. If your company uses more than one Outlook version, download a template for each version.
2. Select Start > Administrative Tools > Group Policy Management to open the Group Policy Management Console.
3. Create a new GPO in the required domain.
4. Enable the setting for each Outlook version in your environment.

Downloading the Office Administrative Template

Download the template for each Office version you use:

Office version	Download
2013	Office 2013 Administrative Template files (ADMX/ADML) and Office Customization Tool
2016, 2019, Office 365 ProPlus	Administrative Template files (ADMX/ADML) and Office Customization Tool for Microsoft 365 Apps for enterprise, Office 2019, and Office 2016

Creating the GPO

1. In the Group Policy Management Console, select the domain. Open the Action menu, or right-click the domain, and select Create a GPO in this domain, and Link it here…
2. In the New GPO window, enter a name for the GPO, and click OK.
3. Right-click the new GPO, and click Edit.
4. Expand User Configuration > Policies > Administrative Templates, and select Administrative Templates.
5. Select Action > Add / Remove Templates…
6. Select Add, go to the folder where you extracted the Outlook templates, and select the file for your Outlook version: outlk15.adm for Outlook 2013, or outlk16.adm for Outlook 2016, 2019, and Office 365 ProPlus.
7. Select Close.

Create the GPO · In the domain's menu

Name the GPO · Then OK

Administrative Templates · Under User Configuration > Policies

ADMX and ADML files

Copy outlkxx.admx to C:\Windows\PolicyDefinitions, and outlkxx.adml to the language folder, for example C:\Windows\PolicyDefinitions\en-US. Here xx is 15 for Outlook 2013 and 16 for Outlook 2016.

Enabling the setting for Outlook 2013 and 2016

1. Go to Microsoft Outlook 2013 (or Microsoft Outlook 2016) > Outlook Options > Mail Format.
2. On the right, enable Do not allow signatures for e-mail messages. This disables signatures in Outlook 2013 (or Outlook 2016).

Existing signature files stay on computers

The setting disables the signature options and prevents users from adding Outlook signatures. The existing signature file stays on the client computers, and must be deleted manually.

What’s next

• Disable email signatures in Outlook for Windows using Intune: disable Outlook signatures with Intune instead.
• How does Opensense work with Microsoft 365?: how Opensense applies signatures in Microsoft 365.