Open MailManager.Preferences.exe which is located in the Mail Manager installation folder e.g. C:\Program Files\Mail Manager\x86
 
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For first time use the following window will appear: 
 
 
 
 
 
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The following Admin Preferences window will appear:

For more information about each section see:
Note: Changes will only be applied after saving if the Shared Configuration Folder has been implemented, see step 6 (Multiple PC installations).