What is the primary function of the IMAP4 protocol?

The primary function of the IMAP4 protocol is to store emails on the server, which is essential for managing email effectively across multiple devices. IMAP, or Internet Message Access Protocol version 4, allows users to access their email directly from the server without needing to download the messages to a local device, maintaining all copies of emails on the server. This means users can read, organize, and search through their emails while ensuring that changes are synchronized across all devices, such as smartphones, tablets, and computers.

In contrast to other protocols like POP3, which primarily downloads emails to a device, IMAP4's design philosophy centers around server-side management. Therefore, users can conveniently access their emails from various locations without the risk of losing messages as they are consistently stored on the server. This functionality is critical for modern email usage, where cloud-based systems and accessibility from multiple devices are standard.