title: Does the POP3 protocol allow you to specify a subset of emails to download?
body: <p>I am writing a POP3 mail client. I want to leave the messages on the server, but I don't want to have to redownload all messages every time I reconnect.</p>
  
  <p>If I download all the messages today, and reconnect tomorrow does the protocol support the ability to only download the messages from the last 24 hours or from a certain sequential ID? Or will I have to redownload all of the messages again?</p>
  
  <p>I am aware of the Unique IDentification Listing feature, but according to <a href="http://www.faqs.org/rfcs/rfc1939.html" rel="nofollow noreferrer">http://www.faqs.org/rfcs/rfc1939.html</a> it's not supported in the original specification. Do most mail servers support this feature?</p>
  
  <p>Yes, my client supports IMAP too, but this question is specifically for the POP servers.</p>