Chess Skills: Correspondence Chess on the iPhone

8 Chess Apps and Websites (2021): Chess.com, Lichess, SocialChess, Shredder Chess

Play – Chess Earth

The right way to prepare openings : r/chess

Computer chess - Wikipedia

Correspondence chess - Wikiwand

Chess By Post on the App Store

The Strategic Penpals Who Play Chess by Mail - Atlas Obscura

Why Correspondence Chess Is Still Popular Among Elite Players - The New York Times

ChessJournal App - The Chess Improver

chess ios

Your Move correspondence chess app for iPhone/iPad! - MyChessApps