Summarize the key functional components of the Internet mail architecture. Explain the basic functionality of SMTP, POP3, and IMAP. Explain the need for MIME as an enhancement to ordinary e-mail. Describe the key elements of MIME. Understand the functionality of S/MIME and the security threats it addresses. Understand the basic mechanisms of STARTTLS and its role in e-mail security. Understand the basic mechanisms of DANE and its role in e-mail security. Understand the basic mechanisms of SPF and its role in e-mail security. Understand the basic mechanisms of DKIM and its role in e-mail security. Understand the basic mechanisms of DMARC and its role in e-mail security. .