I can't decide if this is strategic networking of a mentor or pushing nepotism...

There's a slight duplicity inherent in the ethics of these questions, namely that we have an exaggerated notion of fairness and still want to tip the scales towards a favorable outcome.

The entire point of networking is to gain some advantage that would not exist by being outside the network. In that sense, strategic networking is already oriented towards some inequity. So is almost every action we do to gain a competitive edge. Nepotism just shifts the inequity from a win-win to a win-lose (candidate-university).

It doesn't seem like there should be any ethical dilemna here.

I can't decide if this is strategic networking of a mentor or pushing nepotism...

There's a slight duplicity inherent in the ethics of these questions, namely that we have an exaggerated notion of fairness and still want to tip the scales towards a favorable outcome.

The entire point of networking is to gain some advantage that would not exist by being outside the network. In that sense, strategic networking is already oriented towards some inequity. So is almost every action we do to gain a competitive edge. Nepotism just shifts the inequity from a win-win to a win-lose (candidate-university).

It doesn't seem like there should be any ethical dilemma here. That is to say, sending the email is unfair to all the candidates who don't have an advisor like you, but that isn't your burden to bear. This would be self-evident if we accept that a large number of our daily actions are unfair, and that the exalted notion of fairness is an idealism that we don't live up to.