Why It Matters
POP3 is one of the oldest email protocols still in use, and while IMAP has largely replaced it for most people, POP3 still has its place. It's simpler, uses less server storage, and works well for single-device setups where you want a local copy of everything. If you're archiving email or working with legacy systems, you'll likely encounter POP3.
How It Works
Your email client connects to the mail server on port 995 (encrypted) or 110 (unencrypted -- don't use this). It authenticates with your username and password, downloads all new messages, and -- by default -- deletes them from the server. Some clients offer a "leave a copy on server" option, but it's not as seamless as IMAP's built-in sync.
The protocol is stateless and simple: connect, list messages, download, delete, disconnect. There's no concept of folders, flags, or read/unread status on the server side.
Quick Tips
- Use IMAP instead of POP3 if you check email on multiple devices -- POP3 doesn't sync between them
- If you do use POP3, always enable SSL/TLS to encrypt the connection
- POP3 is still useful for automated scripts that need to fetch and process incoming emails