I often find cases like in number 3, I don't know why there are so many messages about this on my email, I know they tried hacking with phishing. They act like exchange sites or wallets, and their mode asks for certain verification so that your account isn't blocked by them, and you are directed at their site which is very similar to the original exchange site. I don't know how they knows email of bitcoin users?
Can be because of two reasons, the most common one is that you registered in a lot of sites with your mail and they sold your address in a list along with a bunch of other address probably so you get added to the list. Selling information is very profitable online, it's the information age at the end.
Have to be really careful with first which links you click and second what you download.