/ˌpiː-oʊ-piː-ˈθriː/
n. “Download it, then it’s yours… maybe.”
POP3, short for Post Office Protocol version 3, is a standard protocol used by email clients to retrieve messages from a mail server. Unlike IMAP, which keeps messages on the server and synchronizes across devices, POP3 generally downloads emails to a single device and, by default, deletes them from the server, making local storage the primary repository.
Introduced in the mid-1980s and refined through version 3 in 1988, POP3 was designed for simplicity and low bandwidth usage. It works over TCP, typically using port 110 for unencrypted connections and port 995 for secure connections via TLS or SSL.
A typical POP3 workflow: the email client connects to the server, authenticates the user, downloads all new messages, and then optionally deletes them from the server. Users could also configure clients to leave copies on the server for a period of time, but the protocol’s design favors local access and management.
POP3 is lightweight and well-suited for scenarios where a single device needs access to email without worrying about synchronization or multiple endpoints. This made it popular in early home computing and with intermittent connections like dial-up, where keeping emails on the server was impractical.
One limitation of POP3 is multi-device inconsistency. If you download messages to your laptop, they may no longer be available on your phone unless the client is specifically configured to leave copies on the server. IMAP largely solved this problem by keeping messages centralized and synchronized.
Security-wise, POP3 should always be paired with TLS encryption to prevent credentials and message contents from being exposed during transmission. Many modern email services still support POP3 for legacy clients, but its usage is declining in favor of IMAP and web-based interfaces.
POP3 interacts seamlessly with message formats like MIME, allowing emails to include attachments, rich text, and structured headers. Despite its age, it remains a reliable protocol for lightweight, single-device email access and archival.
In short, POP3 embodies a “download and own” philosophy: simple, efficient, and historically foundational, but less flexible for the multi-device, cloud-connected world of modern email.