How to let gnus to fetch only newest email instead of fetching from the 1st one?

[Binjo]

Hi,

I'm using Gnus v5.13 under windows, with the following settings to read email:

(setq gnus-secondary-select-methods '((nntp "news.gmane.org")
                                      (nnimap "gmail"
                                              (nnimap-address "127.0.0.1")
                                              (nnimap-server-port 9939)
                                              ;;(nnimap-stream ssl)
                                              )
                                      (nnml "another.pop.server")
))

(setq mail-sources
      '((imap :server "127.0.0.1"     ;;; stunnel to gmail
              :port 9939
              :user "binjo.cn"
              :predicate "1:*"
              :fetchflag "\\Seen")

        (pop :server "another.pop.server"
             :user "binjo"
             :password "password")

        ))

The nnimap is OK for me to read & send email, whereas the pop is not working as
I expected. Whenever I start the gnus, it always fetch email from the 1st one,
not the newest one. And in my directory of "~/Mail/mail/misc", the filename is
still increasing, e.g last time fetched email is 123, this time it will be 124,
and this 124 is exactly the same to the 1 email...

I've tried to search via Google to resolve this, but with no luck. Is there any
settings I missed to let Gnus only fetch newest email?

Thanks in advance for your help.

Binjo

-- 
Life is like a prison, can you break it?