POP3, or Post Office Protocol version 3, is a protocol used by email clients to retrieve email messages from a mail server. It operates over TCP/IP networks and allows users to download emails from the server to their local devices for offline access.
POP3 operates over TCP (Transmission Control Protocol). TCP ensures reliable communication by establishing a connection-oriented session between the client and the server. This connection-oriented nature of TCP ensures that data packets are delivered in sequence and reliably, which is crucial for email retrieval operations.
POP3 is a pull protocol, meaning that it requires the email client to initiate communication with the server to retrieve messages. When a client connects to a POP3 server, it sends commands to request email messages and then downloads them to the client’s device. This contrasts with push protocols where the server initiates communication to deliver data to the client.
POP (Post Office Protocol) and IMAP (Internet Message Access Protocol) are two protocols used for email retrieval. POP is simpler and typically downloads emails to the client’s device, deleting them from the server by default (although settings can be adjusted). IMAP, on the other hand, allows users to manage emails directly on the server, enabling synchronization across multiple devices and maintaining a copy of emails on the server.
POP3 traffic uses TCP port number 110 by default. This port is designated for POP3 communication between the client and the server. When configuring email clients to connect to a POP3 server, users typically specify the server address (e.g., pop.example.com) and port number (110 by default, or 995 for POP3 over SSL/TLS).
