full date and simplification

muttrc

@@ -13,8 +13,8 @@ set editor = $EDITOR
 set timeout = "5"
 set mail_check = "10"
 set mailcap_path = ~/.config/mutt/etc/mailcap
-set date_format="%m/%d %I:%M"
-set index_format="%2C %Z %?X?A& ? %D %-15.15F %s (%-4.4c)"
+set date_format="%y/%m/%d %I:%M"
+set index_format="%2C %zs %?X?A& ? %D %-15.15F %s (%-4.4c)"
 set markers = no
 set mark_old = no
 set mime_forward = yes