What is a computer on the internet that operates like traditional post office?

A computer on the internet that operates like a traditional post office is often referred to as a mail server. Just as a post office receives, sorts, and delivers physical mail, a mail server handles the sending, receiving, and storing of email messages. It uses protocols like SMTP for sending emails and IMAP or POP3 for retrieving them, ensuring that messages are properly routed to their intended recipients.