POP-3 Server

About

A POP3 mail-retrieval server implemented in C for ITBA's networking course. It follows the POP3 protocol's command/response state machine over TCP sockets, serving mail clients exactly as the specification prescribes.

Key Features

• Implements core POP3 commands (USER, PASS, STAT, LIST, RETR, DELE, QUIT) across the AUTHORIZATION, TRANSACTION, and UPDATE states.
• Handles multiple simultaneous client connections over TCP sockets.
• Follows the POP3 RFC so standard mail clients can connect unmodified.

Technical Challenges

• Implementing the POP3 state machine so commands are only accepted in valid states.
• Multiplexing many concurrent client connections without blocking.
• Parsing and answering the line-based protocol exactly as clients expect.

Impact & Results

Deepened a practical understanding of application-layer protocols and socket programming in C.

Technologies Used