@substitution.setter<EOL><INDENT>def substitution(self, substitution):<DEDENT>
if isinstance(substitution, list):<EOL><INDENT>for s in substitution:<EOL><INDENT>self.add_substitution(s)<EOL><DEDENT><DEDENT>else:<EOL><INDENT>self.add_substitution(substitution)<EOL><DEDENT>
Add substitutions to the email

        :param value: Add substitutions to the email
        :type value: Substitution, list(Substitution)