Computers in correspondence chess In competitive correspondence chess, can humans win at all against computers? Do humans contribute at all to the game?

Provided that it is allowed by the rules, I fail to see how it is not just testing who has the best computer or the best computer program. In this scenario, the players would just be an interface, or not even that, since the computer can also send a move through the internet to the opponent.
I must disagree completely with the above answer. In the correspondence tournaments that I have participated in using a computer was considered cheating and if you were the tournament winner you had to do an analysis of one of your winning games, chosen by the tournament directors, to prove that you knew what you were talking about. 

Second the computers main advantage against human players is their speed. A computer calculates thousand upon thousands of instructions per second and is able to analyse thousand of possible moves on each of its turns. However the computer has no true intelligence, which a human player does. The computer program Hydra was built to completely dominate the chess world and it did in fact beat every other chess program in the the world and has never been beaten by a human over-the-board. However it was beaten by a correspondence player in two games and drew their third game. I have been unable to find if the player consulted a computer or not, but as was pointed out in the discussions of the games on www.chessgames.com the player, correspondence chess International Grandmaster Arno Nickel, wasn't simply following another program since Hydra could beat all other programs as the time. 

To say that unaided humans have no chance at all as though it were an obvious given is simply wrong. Take away the time constraints, have a motivated skilled correspondence player and there is a strong chance that the player will still win.

Hydra ran on a specially designed system that spread the processing required out over a network and is the only chess engine that would have a chance against the correspondence world champions if they were not constrained by time controls.