store sensitive mail server name and email account password in appsettings.Development.json during the development process

In an ASP.NET Core application, you can use appsettings.Development.json to store user secrets by leveraging the built-in Secret Manager tool. The Secret Manager tool allows you to store sensitive data, such as passwords, API keys, or connection strings, outside of your code and configuration files, in a safe and secure way.

appsettings.Development.json is a configuration file used in ASP.NET Core applications for storing configuration settings specific to the development environment.