Which of the following protocols supports encryption for email?

Postfix is an open-source mail transfer agent that is designed to route and deliver electronic mail. It does support encryption methods for email communications, particularly through the use of Transport Layer Security (TLS) which can encrypt messages that are sent between mail servers. This ensures that the contents of emails are protected from eavesdroppers during transmission.

While SMTP is a protocol that is used to send email and can be secured with TLS, simply stating SMTP does not explicitly indicate its ability to support encryption like Postfix does in its operational context. IMAP primarily deals with retrieving and managing emails on a mail server and has its own security mechanisms, but it is not responsible for the transmission of email between servers. NTP, which stands for Network Time Protocol, is unrelated to email transmissions altogether, as it is used for synchronizing time across computer systems.

Thus, Postfix stands out as the option that directly represents a protocol or application designed with an emphasis on secure email delivery through encryption practices.