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# What is POP3?

| What is POP3?
---
**POP3**

![](https://storage.crisp.chat/users/helpdesk/website/67938060e89a4400/pop3_siq83s.png)

As shown in the figure above, the **Post Office Protocol** or **POP** is used to retrieve email messages from a mail server to a mail client.
The latest version, which is what's widely used, is version 3 - hence the term **POP3**.

**POP** version 3, which is specified in **RFC 1939**, supports extensions and several authentication mechanisms.

Authentication features are necessary to prevent malicious individuals from gaining unauthorized access to users' messages.

Generally speaking, a **POP3** client retrieves email in the following manner:

* Connects to the mail server on port 110 (or 995 for SSL/TLS connections)
* Retrieves email messages
* Delete copies of the messages stored on the server
* Disconnects from the server

Although **POP** clients may be configured to allow the server to continue storing copies of the downloaded messages, the steps outlined above are the usual practice.
Leaving them on the server is a practice that's usually done via **IMAP**.