Tasks linked to customer contacts are good, but the ability to have tasks AND subtasks would be great.

Our manufacturing company frequently works with customers on multiple projects that run in parallel. Each project has one to two dozen discreet tasks associated with it. Each task would represent a project overall. Linked sub-tasks would represent what needed to be accomplished on each project.

We don't need the complexity of MS Project but we need more than one level task lists (or the one level task list with check boxes in the Office 365 Planner).

I discussed this issue 20 years ago with Tom Rizzo at Microsoft. Then, my question was "Why can't individual Outlook task lists sync with assigned tasks in Public Folders task lists?) As I understood it, the answer was the limitations of the Exchange architecture... i.e. that Exchange was originally designed as an email system. Then, in response to Notes/Domino (a comprehensive "groupware" product with a relational database on the back end) coming on the market, Microsoft adapted Exchange and created Outlook with tasks, notes etc. However, since the Exchange back end was not a relational database, Exchange tasks were actually attachments to a hidden email acting as a "container." Are we still dealing with that kind of limitation? I've heard Microsoft representatives say that they don't offer subtasks because only a small percentage of customers use Outlook's task functionality to begin with. But, if it is possible, what is lost if sub-tasks are added?