User:Dasch/Thunderbird/Message Categories

Message Categories resemble the Saved Search Folders, except they go even further in terms of dynamism and flexibility. They're meant as a completely alternative to hierarchical folders.

A Message Category is a named set of message filters. These filters can include sender, date, subject, receiver, content, number and kinds of attachments, etc. Furthermore, there are two boolean message properties that can be used in a filter; whether the message is marked as junk and whether it has been marked as deleted.

The "Junk" category would then have a single filter that matches all messages marked as junk. The "Trash" or "Deleted" category would contain all messages marked as deleted. All other categories would by default exclude these messages.

Tags could also be used to categorize messages. For instance, the category "Firefox" could contain a filter that matched all messages tagged "firefox".

Nested Categories

Categories can be nested, in the sense that a subcategory can contain a subset of its parent's messages. A subcategory can never include messages not included by its parent. If the "Firefox" category had a subcategory labeled "Bon Echo", that included messages tagged "bon echo", it would contain only messages tagged both "firefox" and "bon echo".