Watch the Block Chord Position: Major online guitar lesson by Marcy Marxer from Mandolin for Guitar Players
Block chords stretch the left hand and particularly the pinky so be careful not to over use them at first. Covering all the strings in block fashion allows you to play with the extra power needed for musical genres like bluegrass and swing. Played 3, 2, 5, 7. Get your fingers in place, then play with a quick right hand strum and slightly lift the fingers of your left hand to mute the strings. Move this position up and down the neck of the mandolin to play every major chord.