The everyday problem
An inbox may contain several kinds of work that happen to arrive through the same channel. Treating every item as the same task makes routing and prioritization difficult. A useful first step is to understand the categories and their required next actions.
A practical approach
Define a small set of categories with clear ownership and completion criteria. Separate informational items from tasks requiring action. Review ambiguous examples with the team so that categories describe the work rather than only the document format.
Try this with your team
Sort ten fictional incoming items into categories. For each category, write the next action and the role responsible for confirming completion.