Hi,
We can design this SAAS based process automation platform for you. Where you will be able to merge your mail. This application will be created with option like Sign up, Sign in, My Account, and payment panel. We will assign you an expert and experienced team for this project.
The application will provide solution for merging mails, track mails, Save templates draft, and other tasks you mentioned in description. This will be designed in PHP with all the features as per your requirement.
We are ready to work.
Let's discuss further on chat.
Thankyou