What It Is
POP3 stands for Post Office Protocol, version 3. It is an older method for collecting email. Your email program connects to the server, downloads new messages to that one device, and by default often deletes them from the server. It works like emptying your post office box into a bag and taking it home. The mail is now in one place only.
Why It Matters for Your Business
POP3 made sense when people used a single computer and servers had little space. Today it can cause real problems. A business owner who set up POP3 years ago might find that emails read on the office desktop never appear on their phone, or that years of client correspondence vanish when that old computer finally dies.
Good to Know
If you are still on POP3, consider switching to IMAP so your mail lives on the server and syncs across devices. Before switching, make sure messages that exist only on your computer are backed up, because changing the setting does not move old mail back to the server automatically. Some email programs let you upload local folders afterward.