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POP3 Protocol

POP3 is the most basic email protocol for collecting mail which is in common use.

Almost all email client programs (such as Microsoft Outlook & Outlook Express, Mozilla Thunderbird, etc) can collect mail using POP3.

With POP3, mail is usually downloaded by the email client and stored on the user's local PC. It is then deleted from the mail server, so the only copy is on the user's PC. Any mail folders etc are all managed on the user's PC.

You can set a POP3 mail client not to delete messages after downloading them, but this will slow mail collection down over time, as there is no fast way for the email client to just see new messages, each time it checks for new mail it will have to get a list of all the messages waiting on the server, and compare them with the messages it has previously downloaded. If there are many thousands of messages waiting, this operation can be time consuming.

Another limitation of POP3 is that only one email client can access a mailbox at once. This means that mailboxes cannot be shared.

IMAP4 is a more modern email collection protocol which overcomes these problems, allowing shared access to mailboxes, and long term mail storage on the server.

faq/pop3.txt · Last modified: 2018/11/14 10:45 (external edit)