There cannot be a black and white answer given to every matter of application. We have the guidelines of Quran as to stay away from ‘fawahish’, one has to decide for himself / herself to take every measure in his/her power to stay away from acts which lead to ‘fawahish’ or to ‘Zina’ being its extreme form. Of course, the sensitivity will logically increase when massage is being done by an opposite gender person, while it would stay low if it being done by the same gender person. But in all circumstances, one has to be mindful of not engaging in the kind of massage that would increase the risk of it being entering into category of ‘fawahish’. Other than that, massage cannot by nature be declared prohibited.