Hello,
I have over 15 years experience with various programming languages and technologies. I have done many projects that require popup boxes, modals and input verification. I can complete this project for you in a matter of hours (tomorrow, it's VERY late here right now).
Please see my certifications and customer reviews for my credentials, I have some website links in my portfolio that you can check out that demonstrate captcha validation, email validation and other features that would directly relate to this project.
I am a true professional and provide only top notch work, I'm sure other coders will under bid me but I can assure you that you will not receive anything near the quality and reusability of code that I provide.
Before continuing I will need to know how you would like to codes to be stored on the back end and what if any specifications you have or will need about retrieving these codes into your mailing system.