Do any of you use the macOS Mail App? I stopped using it years ago, but I know it is the go-to Email App for many Mac users. Apparently, the Mail App in the initial release of Catalina is having some serious issues. This article describes what some of the problems are and they advise not upgrading to Catalina until this issue is fixed. If you have already upgraded to Catalina, they advise checking through your Email to see if any of the described issues exist.