Here are described the following variables.
If `mew-use-highlight-cursor-line' is `t', underline is put on the cursor line in Summary mode. The default is `t'.
If `mew-use-highlight-mouse-line' is `t' on XEmacs, the mouse line is painted in Summary mode. This is very convenient to read messages clicking the middle button of the mouse. The default value on XEmacs is `t'.
If `mew-use-highlight-mark' is `t' and you are in Summary mode on one of folders enumerated in `mew-highlight-mark-folder-list', marked lines are painted. The default of `mew-highlight-mark-folder-list' is '("+inbox") and that of `mew-use-highlight-mark'is `t'. If `mew-highlight-mark-folder-list' is set to `t', maked lines in all folders are painted.
If `mew-use-highlight-header' is `t', a header is painted in both Message mode and Draft mode. The default is `t'.
If `mew-use-highlight-header' is `t', a body is painted in both Message mode and Draft mode. The default is `nil'.
If `mew-use-highlight-url' is `t' , strings containing URL are emphasized in Message mode. The default is `t'.
If `mew-use-highlight-x-face' is `t' on XEmacs, X-Face: in a header is iconified in Message mode. The default value on XEmacs is `t'.