What is POP3?

POP3 (Post Office Protocol 3) is an Internet protocol for receiving and retrieving e-mails.

Using POP3, a recipient can download his e-mails from a mail server and open, edit and save them on his client device. However, this is not done synchronously with the server. This means that read and edited emails are not marked the same on all end devices (smartphone, tablet, desktop, webmail, etc.). If you download messages using POP3 and do not explicitly leave them stored on the server, they will only be available on the end device on which you downloaded the message. Any other end devices would not receive the message again.

An advantage of POP3 is the fact that it does not require a permanent Internet connection. Once the email messages are downloaded, you can open them again at any time. If you do not store your messages on the mail server, POP3 mailboxes consume very little space on the server.

The biggest disadvantage is that once downloaded, mails can only be found on a single device, as they are also deleted from the mail server. In the settings of the e-mail client, you can define how long e-mails should remain on the server.

For modern e-mail systems, the use of POP3 is not recommended, because most people use several e-mail clients for mail retrieval and only with IMAP the same data status exists everywhere.

See also:
Wikipedia: POP3