Simple batch email sending system by customizing CMS

Create a simple web application based on existing CMS. Propose and extend an existing CMS (to avoid reinventing the basic functions) to create new functionality. This is a rather straight forward and simple project. FIVE primary requirements: 1. Create new tables in the CMS DBMS. 2. Create new web pages for CRUD the data for the newly created tables in the CMS. 3. Create a custom webpage and module to send emails based on email server configuration (provided by user, stored in database) and email file (.eml / .msg files are email files) - (totally different from the default "email notifications" function in CMS) 4. Accept payment from major credit cards & paypal and store payment transaction data in the database 5. Define three user categories (free user, paid user, super paid user) and restrict web page access based on these user categories. Additional information provided: - Database tables names, schema, data types will be provided (I am a developer but I do not have the time to do this, that is why.) - Items 1, 2 & 5 is quite straightforward and can be fairly quickly - Item 3 is totally customized and most of the work will spent on this part. - Item 4 can be leveraged on existing payment providers such as Paypal. Expectations: - Code must be maintainable with future versions of CMS. The custom extension must be modular. - The CMS can be in ANY of the following language (Java, PHP, .NET). As long as the CMS is well known, well supported and it fits the requirements. Other proposals can be considered