I need to create a text UDF for all items in the outlook todo list. I want to call this "WBS", and it needs to apply to task items as well as anything else I put in the todo list.
I guess this means that it has to be created at "folder" level rather than at "item" level, as I need it to be editable directly in the todo list without going into each folder one-by-one.

The issue I'm facing is that once I set it in, say, the "tasks" folder, I can no longer ALSO set it up in the "inbox" items as the name has already been used.

If I create it at item level, then how can I edit it in the to-do list view? (and for that matter, where can I edit it in the item UI itself as I can't find it?)

Are there any built-in text fields which are common to all task/mail item types?

Alternatively, must I create a "taskitem" from each inbox message that I want to followup, just so I can add a WBS to it? How easy is it to do that?