How to prevent Outlook from adding signatures
After installing centrally managed signature adding software (such as CodeTwo Exchange Rules or CodeTwo Email Signatures for Office 365), you might need to disable personal signatures added in Outlook. If you are not able to get all users to manually remove their Outlook signatures, some users may end up having two different signatures: one made by Outlook and another added by the signature adding software operating server-side.
Your users need to be logged on to a domain to which you have full administrative access, because they have to be subjected to your GPO policies for this solution to work. Organizations working with Exchange Online (Office 365) can also apply this solution if their users are connected to the on-premises Active Directory or Azure AD to which you have full administrative access.
To avoid the above-mentioned problem, you can use Group Policy Object. If you don't have the ADM or ADMX file dedicated for the Outlook version used by your users, you should download one. Use the appropriate link from the list below:
- Office 2003 - link no longer available
- Office 2007
- Office 2010
- Office 2013
- Office 2016
- or find it yourself on the Microsoft Download website.
This solution requires a Security Group containing all users who should not have their signatures set up by Microsoft Outlook. If you do not have such a Security Group (e.g. Users with no signature - see Fig. 1.), create a new one directly under your domain.
The next steps depend on your environment. Use the links below for guidelines.
Both the ADMX and ADML files are necessary to complete the installation. For more information on these files, see this article.
To install Policy Definitions in Windows Server 2008 and newer environments, place all the ADMX files inside the directory:
The ADML files are a significant part of the policy definition and must be installed along with the ADMX files. Inside the PolicyDefinitions folder you will be able to see at least one directory with a name corresponding to your locale, e.g. en-US. Inside the downloaded package, you should find a lot of similar directories. In order to complete the installation of policies, please follow the steps below:
- Ensure that you have opened the PolicyDefinitions folder and the download location (Fig. 2.).
- Find out what directories with language-based names are existing both in PolicyDefinitions and in the download location.
- In the download location, copy the folders whose names are also found in the PolicyDefinitions folder.
- Paste the copied folders into the PolicyDefinitions folder.
Prior to taking this step, please ensure that you have a relevant Security Group containing all users who should not receive any signatures added by Microsoft Outlook. Open the Group Policy Management Editor by running gpmc.msc and follow the steps described below:
- In the left pane, right-click on your domain (e.g. domain103.lab) and select Create a GPO in this domain, and Link it here.
- Name your new GPO (e.g. No signatures) and click OK.
- Select the newly created object to open it.
- On the Scope tab, remove Authenticated Users from the Security Filtering pane.
- In the same pane, add the Security Group that you created earlier (e.g. Users with no signature), as shown in Fig. 3.
Finally, right-click on the GPO in the right pane and select Edit from the shortcut menu. In the window that appears, navigate to User Configuration > Policies > Administrative Templates (or Classic Administrative Templates) > Microsoft Outlook  (the number depends on your Outlook version) and Outlook Options, then Mail Format (Fig. 4.).
In the right pane you will see the Do not allow signatures for e-mail messages option. Enable it, as shown in Fig. 4.
All users have to log out and then log in for the changes to be applied. Moreover, you can manually force the policy update by running gpupdate /force. Keep in mind that these changes do not take effect immediately because the time of this process depends on your environment's configuration.
- Open Active Directory Users and Computers.
Prior to taking the next steps, please ensure that you have a relevant Security Group containing all users who should not receive any signatures created by Microsoft Outlook.
- Right-click on your domain.
- Choose the Properties, Group Policy tab and click the Open button. The Group Policy Management console should appear.
- Right-click on your domain (e.g. sbs2003.local) and from the shortcut menu select Create and Link a GPO Here.
- Name your new Group Policy Object.
- Select the newly created GPO in the left pane and ensure that you have opened the Scope tab.
- In the Security Filtering pane add the Security Group you prepared earlier and then remove Authenticated Users from the list.
- Once it is done, right-click on your GPO in the left pane, then select Edit.
Group Policy Object Editor shows up. Expand Administrative Templates. To install the previously downloaded policy definitions, right-click on Administrative Templates and select Add/Remove Templates. A new window will appear (Fig. 5.).
Click the Add button and select the ADM files, then click Close.
Now you are able to set policies to remove current signatures in Microsoft Outlook. To do so, please expand the Administrative Templates and select Microsoft Office Outlook XXXX (where XXXX stands for the version of the installed Office templates). In the figures 6. and 7. below you can see where the relevant policies are located in Office 2003 and Office 2007.
To disable adding Outlook signatures to messages, set the options highlighted in Fig. 6. and 7. (depending on your Outlook version) to Enabled. Additionally for Outlook 2003, make sure that both options (Disable signatures for new messages and Disable signatures for replies and forwards - see Fig. 7.) are configured as shown in Fig. 8.
All users have to log out and then log in for the changes to be applied. Moreover, you can manually force the policy update by running gpupdate /force. Keep in mind that these changes will not take effect immediately because the time of this process depends on your environment's configuration.
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