Mac OS X file locations

Where does Mac OS X store data files?

Mail files are stored in (hidden) Library sub-directories

~/Library/Mail
~/Library/Mail/V6 (Mojave)

mail preferences are in the ‘com.apple.mail.plist’ file, stored in the /Library/Preferences directory

more details can be found at about tech

Contacts are stored in (hidden) Library Application sub-directories

~/Library/Application Support/AddressBook

Calendar files are stored in (hidden) Library sub-directories

~/Library/Calendars

Music Artwork files (Catalina) are stored in Library sub-directories

~/Library/Containers/com.apple.AMPArtworkAgent/Data/Documents