What is a program that filters unwanted e-mails known as?

A program that filters unwanted emails is called a spam filter because it is specifically designed to identify and manage unsolicited and often irrelevant messages, commonly known as spam. Spam filters work by analyzing incoming emails based on certain criteria, such as keywords, sender reputation, and patterns of behavior, to determine whether an email should be delivered to the inbox or redirected to a spam folder. This helps users avoid the clutter and potential security risks associated with spam emails.

Other options serve different purposes: a virus scanner is used to detect and eliminate harmful software, a firewall is designed to protect networks from unauthorized access or threats, and an ad blocker prevents advertisements from being displayed while browsing the web. Each of these tools plays a critical role in digital security and user experience, but they do not specifically target unwanted emails like a spam filter does.