When you open your Mail, or any, program on a mac the ability to use the scroll bar to move up and down is not always present and it is a real pain to find and use. Can the scroll bar just remain visible all the time?
Yes. All you need to do is change the setting in System Preferences. Open System Preferences, click General and look for the Show Scroll Bars radio box and tick Always.
Close out of System Preferences and re-open your program,
Done.