Even though I have activated the option "If the user's social network profile has no email address, should we ask the user to enter it manually?" and have added a custom message, I am still getting user accounts with email@example.com, from Facebook, Google, and Twitter logins. So far I have 128 such accounts, out of 6,135.
I am using OneAll Social Login 5.0, currently on WordPress 4.5.2, but most of those accounts have been created on previous versions of WordPress. Let me know if you need more information.