I think that there are many unusual features of Tagore's short story. These help to contribute to its greatness. One such feature is the ending. Tagore manages to make the reader feel a sense of disquietude amongst moral ambiguity shrouded in uncertainty in the ending. On one hand, there is a genuine hope or belief in redemption or the Platonic "noble lie," that the Postmaster will come to his senses and return to get Ratan and bring her with him. There is a hope that this will happen even in his mind. Yet, he rationalizes his decision to do nothing and there is a certain experience of feeling that the reader endures as a result. It is easy to criticize the Postmaster for his actions, yet Tagore might be suggesting that, to a great extent, all human beings are guilty, on some level, of this. At some point, we all leave people that depend on us or have left people who possessed great feeling for us. Like the Postmaster, we, too, have rationalized this as being for the best. While we, as the reader, might be quick to throw stones at the Postmaster, one of Tagore's great qualities and something unusual is that we are forced to confront both the Postmaster and our own similar actions.
Another unusual feature would be that the heroine of the short story, Ratan, for all practical purposes, endures a suspended fate, to a great extent. The reader is not necessarily certain as to what is going to happen to this orphan. On one hand, we know she is left behind. She has acquired a certain dignity with the beautiful and loyal manner she displayed to the Postmaster. Yet, we don't know exactly what is to become of her. She stays on in the village, and while we don't know her fate, perhaps, in a genius stroke, all we can do is rationalize and conjecture, like the Postmaster, himself. In another unusual and brilliant move, Tagore reduces the reader to doing the same as the Postmaster regarding Ratan. It is his genius and an unusual feature to the short story to make the heroine subject to wonderment by both her opposite in the story and the reader who reads it.