回复：工作中的麻烦，向大家请教：

You should email the POC and cc boss the first time you found the situation, saying something like "would you please cc me on the email regarding this project?".

I don't think it is a good idea to list all the cases. To you, he will blame your tone, your didn't bring this to his attention the first time....... etc. And how do you know the boss does not blame the POC? To be honest with you, this is what I will do too. This is just business, nothing personal.