The primary function of an email server is to send, receive, store, and manage email communications. Email servers utilize standard protocols like SMTP (Simple Mail Transfer Protocol) for sending emails and IMAP (Internet Message Access Protocol) or POP3 (Post Office Protocol) for retrieving emails. They ensure messages are delivered correctly to the intended recipients, handle multiple accounts, and provide features like spam filtering and security. Email servers are critical components of modern communication, facilitating both personal and professional interactions.