What are you talking about? Just two different scopes, one with email and one without would be enough! Email belongs to user, not twitter, so it’s up to user to decide if (s)he wants to disclose it or not. The point is that users WILL KNOW if email is sent if they make this choice.
Two+ years developers are asking about this and Twitter redirect our words into > nul. That sucks as many people says. Sign in with twitter to get what? Twitter Id? And how do I know that user already exists in my app? Ask them for email? If so then why would I need all this sign in with twitter? To simplify login to my app? Come on!