Which two protocols are commonly used in email transmission?

The two protocols commonly used in email transmission are SMTP and IMAP.

SMTP, which stands for Simple Mail Transfer Protocol, is the standard protocol for sending emails. It is used to transfer messages from a sender's email client to the server and between servers. When a user sends an email, the client uses SMTP to send the message to the appropriate email server.

IMAP, or Internet Message Access Protocol, is primarily used for retrieving and managing email from a server. It allows users to access their emails from multiple clients or devices while keeping the messages stored on the server. Unlike the alternative protocol for retrieving emails (POP3), which downloads messages and can remove them from the server, IMAP maintains the emails on the server for easy synchronization across various platforms.

Together, SMTP handles the sending aspect of email communication, while IMAP deals with the retrieval and management of those emails, making them integral to the functioning of email systems.