Look for the WB'S Mod Page thread in the Mods Workshop forum (may be back a page or two now, but it's there).
Or just go to the Downloads section and do search for a mod called Mission Orders Lite.
It's WB's mod for reducing the radio messages received in the game - should also be a link to it in the first post of his Mod Page thread IIRC.
It will remove all the messages that do not actually give you important information or orders related to your career and gameplay.
