POP (Short for Post Office Protocol) is a protocol used to retrieve e-mail from a mail server. Most e-mail applications (sometimes called an e-mail client) use the POP protocol, although some can use the newer IMAP (Internet Message Access Protocol).
There are two versions of POP. The first, called POP2, became a standard in the mid-80’s and requires SMTP to send messages. The newer version, POP3, can be used with or without SMTP.
POP: Short for point of presence, an access point to the Internet. ISPs have typically multiple POPs. A point of presence is a physical location, either part of the facilities of a telecommunications provider that the ISP rents or a separate location from the telecommunications provider, that houses servers, routers, ATM switches and digital/analog call aggregators.
What does POP mean to you?
You would probably most likely encounter it when setting up your hosted email on your local email client (such as Outlook or Eudora).
POP3 is also referred to as “incoming email” by most of the clients. If you host your own domain and email service, and need to know what your specific POP3 is, you must ask your hosting service provider.
If you use public email services, such as Gmail, there is no need for you to know your POP3.