code: function updateEmailVariables(callback,id,email,variables){
      if ((id===undefined) || (email === undefined) || (variables === undefined) || (! variables.length)) {
          return callback(returnError("Empty email, variables or book id"));
      }
      var data = {
          email: email,
          variables: variables
      };
      sendRequest( 'addressbooks/' + id + '/emails/variable', 'POST', data, true, callback );
  }
docs: Update Variables for an email address in an address book
  
  @param callback
  @param id
  @param email
  @param variables