How can access be restricted or denied to users registered with email addresses in the yahoo.com domain?

To restrict or block access for users with email addresses in the yahoo.com domain, you can implement a check during registration or authentication. For example, in Python, you can verify the email domain and reject registration or login if the domain matches "yahoo.com":

email = "user@yahoo.com"
if email.lower().endswith("@yahoo.com"):
    raise ValueError("Registration with yahoo.com domain is prohibited")

Such a check can be integrated into the registration form or middleware to block access at the application level.