@open_tracking_substitution_tag.setter<EOL><INDENT>def open_tracking_substitution_tag(self, value):<DEDENT>
self._open_tracking_substitution_tag = value<EOL>
Allows you to specify a substitution tag that you can insert in
        the body of your email at a location that you desire. This tag will
        be replaced by the open tracking pixel.

        :param value: Allows you to specify a substitution tag that you can
        insert in the body of your email at a location that you desire. This
        tag will be replaced by the open tracking pixel.
        :type value: string