I made Library visible a long time ago. When I click on it and then on the preference folder, this is what I get, and I see no mail plist.
.bcb53190a25c427979276b98bafe9e9
.GlobalPreferences.plist
Audio
com.apple.airport.opproam.plist
com.apple.alf.plist
com.apple.AppleFileServer.plist
com.apple.apsd.launchd
com.apple.apsd.plist
com.apple.AssetCache.plist
com.apple.BezelServices.plist
com.apple.Bluetooth.plist
com.apple.ByteRangeLocking.plist
com.apple.commerce.plist
com.apple.CoreRAIDServer.cfdb
com.apple.dock.plist
com.apple.driver.AppleIRController.plist
com.apple.FindMyMac.plist
com.apple.HIToolbox.plist
com.apple.iokit.AmbientLightSensor.plist
com.apple.loginwindow.plist
com.apple.MCX.plist
com.apple.networkextension.cache.plist
com.apple.networkextension.necp.plist
com.apple.networkextension.plist
com.apple.noticeboard.plist
com.apple.P2PSupervisor.plist
com.apple.PowerManagement.26C8CDC4-DB76-5021-9111-5A887E6EA221.plist
com.apple.PowerManagement.plist
com.apple.preferences.accounts.plist
com.apple.security.appsandbox.plist
com.apple.security.plist
com.apple.security.systemidentities.plist
com.apple.SoftwareUpdate.plist
com.apple.systemprefs.plist
com.apple.TimeMachine.plist
com.apple.timezone.auto.plist
com.apple.updatesettings.plist
com.apple.ViewBridge.plist
com.apple.windowserver.plist
DirectoryService
Logging
OpenDirectory
org.cups.printers.plist
SystemConfiguration
Xsan
This is getting silly, so it's time for something completely different.
This shows you how to make your home folder permanently visible.
You should be able to take it from there.
