POP3
POP3 (Post Office Protocol version 3) is an Internet standard protocol used by email clients to retrieve email messages from a mail server. It operates on port 110 (or port 995 with SSL/TLS encryption) and typically downloads messages to a local device, deleting them from the server after retrieval. This makes it suitable for single-device access but less ideal for multi-device synchronization compared to modern alternatives.
Developers should learn POP3 when building or maintaining legacy email clients, integrating with older email systems, or understanding foundational email protocols for historical context. It's specifically useful in scenarios where offline email access is prioritized, storage on the server needs to be minimized, or compatibility with simple, low-resource email setups is required, such as in embedded systems or basic desktop applications.