Sin remitente (1995)

A lonely, aging postal worker finds himself the victim of a cruel practical joke in this pessimistic Mexican drama. The trouble begins when crotchety postman Andre begins complaining about his young neighbor Marianna's propensity for playing loud music every time she entertains a lover. To get back at him, Marianna begins sending him anonymous love letters. The old man is intrigued by the mysterious letters and hires a cheap detective to find their author. The detective is convinced the perpetrator is Teresita, a veteran hooker who joins in on the scheme to earn a little extra cash. Andre's friend and colleague tries to warn Andre that it is all a game, but his friend is in love and will not listen. Meanwhile, Marianna attempts to woo Luis Felipe, a hard, unfeeling tabloid journalist who has her take grisly pictures of murder victims for him. Both Marianna and Andre are destined to meet an unpleasant fate at the story's end.

Unfortunately the movie Sin remitente is not yet available on HBO Max.