Does the POP3 protocol support a folder system?

I am working on a email client written in C# and as part of this I wanted to be able to have a folder system for storing emails. Does th开发者_JAVA技巧e POP3 protocol support a folder system?

If it does, which command is it?

POP3 itself does not expose a folder system, but it was invented at a time when a folder was considered a mailbox. Therefore, some systems support a <username>#<mailbox> login. Afterlogic actually has a good explanation here:

http://www.afterlogic.com/support/tutorials-mailbee-net/18-pop3-folders.asp

Basically, on the few systems that support it, to get messages for another "folder" you relogin with a different folder name.

No. A short look at the specifications would have shown you. SMTP does not deal with folders, and POP3 is just a protocol to get an SMTP buffer from a server. Folder management came way later and uses other protocols.

No, POP3 does not support a folder structure outside of Inbox, Sent, etc.

You can reference RFC 1939 for POP3.

If you need a folder structure and sycing you should use IMAP4 (RFC 3501).