I got an email telling me the following “ The Scoop on can’t-miss sessions at Reinvent event” I guess it means that I can not miss the reinvent event, however I am not sure why do they use scoop on here ?
Was this the subject-line of the e-mail? If so, I think they meant, "this e-mail will give you the scoop on can't-miss ...." Where "the scoop" means "the information" (Newspaper reporters supposedly use the expression "the scoop" when they are talking about some exciting information that they have just exclusively learned, and are planning to write a great newspaper article about.)
"Can't-miss" is an adjective describing something you don't want to miss, but it sounds like you already understand that part.
scoop (n): informal A piece of news published by a newspaper or broadcast by a television or radio station in advance of its rivals.
In this case your teaser headline is trying to tell you that the linked news article contains information that you can't find in any other news source. As usual, "You shouldn't believe everything you read".