Is there a way where i can capture the email that bounced after the user registration and create a script to block that account?
One way to disallow bogus e-mails is to validate them during registration process. There are quite few extensions and guides available by simple Google search 'joomla validate email', such as Pre Registration Email Validation plugin or Client-side form validation guide.
There is also another approach for bounce-handling used in commercial newsletter extensions like Acymailing Enterprise and RSMail, which are able to handle such messages and execute actions on wrong receiver such as Delete the user, Block the user etc.
But, writing such a 'script' as you are asking for, requires significant knowledge, experience and a price tag, and I am afraid it exceeds scope of such Q&A site as JSE is.