No person in an establishment as defined in this chapter shall be restrained from sending written communications of the fact of his or her detention in such establishment to a friend, relative, or other person. The physician in charge of such person and the person in charge of such establishment shall send each such communication to the person to whom it is addressed. All persons in an establishment shall have no less than all rights secured to involuntarily detained persons by RCW 71.05.217 and to voluntarily admitted or committed persons pursuant to RCW 71.05.050 and 71.05.380.