Reading Unread POP3 Email

Question:

I'm trying to parse a mailbox based on the unread flag. I've looked at your example and am able to read mail based on a number of filters, (from, to dates etc) but my unread filter doesn't work. Can you tell me how I need to set the filter to pick up only unread mail please?

Answer:

POP3 servers do not keep information regarding read/unread status. It is not possible to read "unread" messages from a POP3 server. IMAP servers however, do maintain this information. Programs such as Outlook keep read/unread status information in their local database for emails coming from a POP3 server.