How to find a systems file on Mac The answer to a previous question (that I share) suggested going to this file ~/Library/Containers/com.apple.mail/Data/Library/Preferences.  How does one find that.  I don't know what ~/ references and the Library files that I find on my hard drive do not have a Container subfile
If you hold down the Option key, your Library folder (~/Library), which is normally hidden, will show up under the Finders Go menu. Just selected it (Go -> Library) and you will be there in the Finder.