Re: "Wrong" email addresses
"I do remember some years ago, that some sites where a bit "snobby" and not excepting users that had email accounts from the likes of Hotmail and Yahoo."
In my recent experience I found the exact opposite. I tried signing up to The Times website so I could read news articles and it utterly refused to accept my email address (I have my own domain). Seeing as it wasn't for anything particularly important I used a throwaway Gmail address and sign-up worked first time.