mm-uu-hide-markers

mm-uu-hide-markers is a variable defined in `mm-uu.el'.
Its value is

nil

Documentation:
If non-nil, hide verbatim markers.
The value should be nil on displays where the face
`mm-uu-extract' isn't distinguishable to the face `default'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 23.1 of Emacs.