email error from sign up page

The sign up page is not accepting email, i tried to test run but reject every email i enter (Please enter a correct email address) and i have used the same page to register and create some sites for testing purpose so i dont know what has gone wrong and secondly Network theme is like theme that display blog post and images on the front page my own site (courtesy Network theme) does the same but without the images , how will i make the image come with the post display….thanks