Iurii Koshmak is 71 years old, a civil engineer, living in Kyiv. He played his first correspondence tournament in 1973. Since 2012 he has been playing regularly on the ICCF server. Besides, he has been delegate for Ukraine to seven ICCF Congresses.

In 2019, Iurii won the Ukrainian Correspondence Chess Championship with 8.5 out of 14, a well-attended tournament with 14 rounds, in which, however, no ICCF title norms could be achieved.. He did, however, earn the latter in the same year in one of the preliminary rounds of the 21^st Correspondence Chess Olympiad, which was held at the same time. There, he won the CCO21/S4 group on board 3 with 7 out of 9 and was the only player to fulfil the GM norm ahead of Norwegian GM Gerild Haugen. He repeated this success at the 23rd Olympiad by winning a preliminary group, this time on board 1, where 5 out of 9 was enough for a GM norm. In 2025, having already earned the GM title, he confirmed it once again with a 1st-3rd place finish at the 5th Marian Vinchev Memorial B1, in which players with an Elo rating between 2450 and 2499 participate.