Sendig mail from GMX fails

[someusernamehere]

Hey  have this in my .gnus file:

(setq smtpmail-local-domain nil
      smtpmail-queue-mail t
      smtpmail-queue-dir "~/mail/queued-mail/"
      smtpmail-default-smtp-server "mail.gmx.net"
      smtpmail-debug-info t
      smtpmail-debug-verb t
      smtpmail-starttls-credentials
      '(("mail.gmx.net" 25 nil nil)))


The problem is that Gnus try to sent the mail for the local postfix (I
mean the server web on my own machine) for example if I stop the
postfix in my machine I can't send mail
and using my local postfix some mails are not send, what is wrong?, I
want to use GMX smtp for send mail.


thanks