Hello Sir,
I have more than 16 years of experience in the development and implementation of websites, including application software. Reading the brief of your assignment, I can understand that you need to have a process/program that could validate all the email addresses you have in your possession so that the wrong ones can be isolated to avoid same to bounce back in the future. This is something which I have been used to do. Should you feel I am the right person to do your job, please feel free to message me - we can then clarify further on the assignment.