I think the real problem is that the people who are so unprofessional and have no work ethic will not even realize the letter is directed at them! I HATE, HATE, HATE passive aggressive-ness! She needs to call the people into the office who are guilty of shopping online, taking multiple breaks, etc, etc. and tell them PLAINLY, "YOU have been shopping online, taking too many breaks, not helping others, etc." Instead, everyone will assume that what they do isn't THAT bad and she can't possibly be talking about THEM....and the exact same crap continues happening.
It's just like when someone puts up a sign. I saw this happen the other day where someone put up a sign to stop ONE staff member from using a door they shouldn't have been using. Why not just approach that one staff member and explain why they can't use it?! Ugh.