This will take me a month. If the previous developer, can insert my code, it will only take a day. I could also, rebuild it from scratch. This will also take around a month. I would need the graphics. If a Google API needs to be used, this will also take longer. Unless, of course, you wanted to store the emails in a MySQL database. In which case, if a person wanted to send an email, they would always need to login to your app. The email addresses, would not work, using any email provider. Anyway, if the emails are handled by a Google API, this will take longer.
If hired, I will report to you, my daily progress.