how to fetch mail from gmail?

[sunway]

this is my configution:

(setq gnus-secondary-select-methods '((nnfolder "")))
(require 'smtpmail)
(setq send-mail-function 'smtpmail-send-it
      message-send-mail-function 'smtpmail-send-it)
(setq smtpmail-smtp-server "smtp.gmail.com"
      smtpmail-smtp-service 587
      smtpmail-auth-credentials `(("smtp.gmail.com" 587 
"sunwayforever@gmail.com" "pass")))
(require 'starttls)
(setq smtpmail-starttls-credentials
      '(("smtp.gmail.com" 587 nil nil)))
(setq mail-sources
      '((pop :server "pop.gmail.com"
             :user "sunwayforever"
             :password "pass"
             :port 995
             :connection ssl
             :leave t)))

when start gnus, it will hang when fetching mail from pop.gmail.com. 

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