"This is an automatically generated email, please do not reply." Thousands of people search that exact sentence every month, often because they replied anyway and got a bounce.

For the sender, a noreply@ address is convenient. For the customer it is a dead end, and replies are one of the signals mailbox providers read as engagement.

Noreply@ belongs to the broader family of addresses tied to a function rather than a person. uChecker's page on role-based email addresses looks at them from both sides: sending from them and finding them in your list.