You can decide not to use the single-sign on for your Messaging and Calendar application - Outlook.
To do this, if you've already opened outlook once with your single sign-on tool, you do not need any additional settings. Just open outlook from the desktop icon or the start menu and it will ask you which profile to use. Make sure you select the profile name which has your current email address. For example, firstname.lastname@example.org . The default profile name when you first used outlook is usually 'outlook' unless you changed it.