My peak was in the 1980s when I qualified for ICCF World Championship play (before computers) by winning two Master tourneys. OTB went 6-1 in a strong event and tied with Dzindzi, Bisguier, and IM Leonid Bass. Dzindzi was staying in Chicago at the time and I drove him to the tournament. Driving home after the obligatory pizza celebration he suddenly turned to me and said "Hey-- you cost me some prize money!"
It is NEVER legal to use an engine to suggest moves on Chess.com. During an online/correspondence game you are free to consult any source you wish, including computerized databases, so long as you are merely accessing the material. If you insist on using an engine please abort our game and play someone else. Thanks and good luck!