It's not recommended to store sensitive information such as email account passwords in appsettings.Development.json or any configuration files, even if it's just for development purposes. This is because if the configuration files are accidentally committed to a source code repository, the sensitive information will be exposed to others who have access to the repository.
Instead, it's better to use a secure configuration provider, such as the Secret Manager tool, to store and manage sensitive information. The Secret Manager is designed specifically for storing secrets during development, and it can store your sensitive information outside of your code and configuration files, in a safe and secure way.
If you are the only person to use your computer and still store source code on Git, you can use the following alternative ( not recomended)
You can exclude the appsettings.Development.json file from Git.
To exclude the appsettings.Development.json file from Git and Team Explorer, you can add it to your .gitignore file. The .gitignore file is a text file that specifies which files and folders Git should ignore when you commit changes to your repository. Here's an example .gitignore file that excludes the appsettings.Development.json file:
# Ignore appsettings.Development.json
appsettings.Development.json
# Ignore other development-related files
launchSettings.json
bin/
obj/
By adding appsettings.Development.json to your .gitignore file, you ensure that it won't be included in your Git commits or pushed to your repository. This way, your sensitive information won't be exposed to others who have access to the repository.