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Type the required folder's name in the Value text box and click Add to List button below. We recommend typing the Projects folder. The name of a folder depends on your localization, please check it.
Click OK, then OK again. You'd now set up a filtered view for your tasks in the Outlook To-Do Bar.
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Check tis video on how to customize your To-Do list with Task manager activities: https://youtu.be/OX_GsShG1qc