Creating message type categories and adding fields

Message type categories are to message types, what message types are to messages: the bundle entity.

With the Message type UI module you can add message type categories and add fields to them. Examples:

Show in history

* Create a message type category "MTC" and add a boolean field to it: "Show in history"
* Attach some message types to that category and set that field like you want
* Create your history view so that only those message types are shown

Send to user

* Create a message type category "MTC" and add a boolean field to it: "Send to user"
* Attach some message types to that category and set that field like you want
* In your rules check the field to decide if message must be sent to user