To provide you with accurate information about web app development costs, I would need more details about the specific requirements and features of the web app you’re looking to develop. Web app development costs can vary widely based on factors such as:

1. Complexity: The complexity of the features and functionalities you want in the web app will greatly impact the cost. More complex apps with advanced features will generally cost more to develop.

2. Design: The design of the user interface and user experience also affects the cost. A more intricate and custom design might increase the development expenses.

3. Technology Stack: The technologies and frameworks used in the development process can influence the cost. Some technologies might require more specialized expertise, which could impact the overall price.

4. Integration: If your web app needs to integrate with third-party services or APIs, this could affect the development time and cost.

5. Scalability: If you need the web app to handle a large number of users or data, the development cost might be higher to ensure the app’s scalability.

6. Maintenance and Support: Consider ongoing maintenance and support costs, as these are essential for keeping the web app functional and secure.

7. Development Timeframe: The timeline for development can also impact the cost. A shorter development timeline might require more resources and could be more expensive.

8. Development Team: The rates of developers and designers involved in the project will contribute to the overall cost. Rates can vary based on location and expertise.

Since you mentioned that you send emails in bulk and want to avoid them going to spam, it seems like you’re looking for a web app related to email communication or marketing. If you could provide more specific details about the features you need and any particular technologies you have in mind, I can offer a more accurate estimate of the development cost. Keep in mind that to ensure your email communication doesn’t go to spam, you’ll also need to implement proper email authentication and anti-spam measures, which might not directly fall under web app development but are important for successful email delivery.