ICCF or Lechenicher, both of them have databases.
Be aware that the ICCF and Lechenicher both allow engine use, but I think the Lechechiner one has some no-engine tournamentes, so you may want to get those databases and filter games by rating.
http://www.chess-server.net/info/home
Are there any known chess databases that consist of high-level (2200 FIDE/USCF rated players) correspondence games only. Correspondence games are much more fun for me to analyze and might help with my opening theory. Thanks!