How to read unread mails from mail server???

Question

Hi to all,
My project has reading mails from mail server.
the mail server is not in OUTLOOK. Its like a Exchange server like gmail,yahoo & so on...
I am reading all the mails & save the attachments.
I am Using the sample Application is.,
http://www.codeproject.com/KB/IP/Pop3MimeClient.aspx
But I can't read UNREAD mails.there is no flag in that application.
So How to read UNREAD mails from mail server???
Thanks,
nkmKrishna