CodeTwo Base.title

How to prevent Outlook from adding signatures

Problem:

After installing centrally managed signature adding software, such as the CodeTwo Exchange Rules family, the Pro version or even cloud based CodeTwo Email Signatures for Office 365, you may need to disable stamping of the messages with personal signatures created 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.

Solution:

Your users must be logged on to a domain to which you have full administrative access as they must 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 an on-premises Active Directory or Azure AD to which you have full administrative access.

To avoid the above-mentioned problem, you may use Group Policy ObjectIf you don't have the ADM or ADMX file dedicated for the Outlook version used by the users, you should download one. Please pick the appropriate one from the list below:

Please keep in mind that this solution requires a relevant 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), create a new one directly under your domain.

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Fig. 1. A Security Group with users who should not receive a signature.

The next section refers to newer environments, so if you are using Windows Server 2003 or SBS2003, click here.

On Windows Server 2008 and newer

First, please note that both ADMX and ADML files are necessary to complete the installation. For more information, please refer to the Microsoft's Knowledge Base article. To install Policy Definitions on Windows Server 2008 and newer environments, please place all the ADMX files inside the directory:

%SystemRoot%\PolicyDefinitions

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 described below:

  1. Ensure that you have opened the PolicyDefinitions folder and the download location.
  2. Find out what directories with language-based names are existing both in PolicyDefinitions and in the download location.
  3. In the download location, copy the folders whose names are also found in PolicyDefinitions.
  4. Paste the copied folders into the PolicyDefinitions folder.

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Fig. 2. Copying files to PolicyDefinitions.

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:

  1. In the left pane, right-click on your domain (e.g. domain103.lab), then select Create a GPO in this domain, and Link it here. 
  2. Name your new GPO (e.g. No signatures) and click OK.
  3. Select the newly created object to open it. 
  4. In the Scope tab, remove Authenticated Users from the Security Filtering pane.
  5. In the same pane, add the Security Group that you created earlier (e.g. Users with no signature).

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Fig. 3. Setting up a new GPO object. 

Finally, right-click on GPO in the right pane and select Edit... from the context menu. In the window which will appear, navigate to User Configuration, Policies, Administrative Templates (or Classic Administrative Templates), Microsoft Outlook 2010 (this number depends on the version you have installed) and Outlook Options, then Mail Format.   

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Fig. 4. Location of the enabled policy.

In the right pane you will see the "Do not allow signatures for e-mail messages" option. Enable it.

All users have to log out and then log in to apply the changes. Moreover, you can manually force the policy update by running gpupdate /force. Please keep in mind that these changes will not take effect immediately because the time of this process depends on your specific environment configuration. 

On Windows Server 2003 or SBS2003

  1. Open Active Directory Users and Computers.
  2. 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. If so, right-click on your domain.
  3. Choose the Properties, Group Policy tab and click the Open button. The Group Policy Management console should appear.
  4. Right-click on your domain (e.g. sbs2003.local) and from the context menu select the command Create and Link a GPO Here...
  5. Name your new Group Policy Object.
  6. Select the newly created GPO in the left pane and ensure, that you have opened the Scope tab. 
  7. In the Security Filtering pane add the Security Group you prepared earlier and then remove Authenticated Users from the list.
  8. Once it is done, right click on your GPO in the left pane, then select Edit... 

Group Policy Object Editor should show up. Once it does, expand Administrative Templates. To install the previously downloaded policies' definitions, right-click on Administrative Templates and select Add/Remove Templates. The following window will appear:

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Fig. 5. Additional administrative templates. 

Click the Add... button and select the ADM files, then click Close. Now you are able to set proper policies to remove current signatures in Microsoft Outlook. To do so, please expand the Administrative Templates and select Microsoft Office Outlook XXXX (where the XXXX stands for the version of the installed Office templates). In the figures below you can see where the relevant policies are located in Office 2003 and Office 2007.

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Fig. 6. Disabling signatures added by Outlook 2007,using Exchange Server.

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Fig. 7. Disabling signatures added by Outlook 2003, using Exchange Server.

To disable adding the Outlook signatures to messages, set the tools marked in the pictures above to Enabled. Additionally, for Outlook 2003, check the two disabling boxes (Disable signatures for new messages / Disable signatures for replies and forwards), as shown in Fig. 8.

How set up disabling signatures from Otlook 2003.
Fig. 8. Additional configuration for Outlook 2003 in Exchange Server.

All users have to log out and then log in to apply the changes. Moreover, you can manually force the policy update by running gpupdate /force. Please keep in mind that these changes will not take effect immediately, because the time of this process depends on your specific environment configuration. 

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