Spam Delivery

I set the spam and virus delivery to ~/Maildir/.Junk/ but identified spam keeps delivered normally.

These are all mail users which normal mails are forwarded to an extern address.

webmin 1.790
virtualmin 1.0.5
usermin 1.690-1
spamassassin 3.3.1-3
spamass-milter 0.3.2-4
postfix 2.6.6-6.0.1
CentOS 6.7

It works now. I had to activate both options in the users “Mail forwarding settings”:
[X] Yes, deliver to mailbox
[X] Yes, forward to addresses

Now clean mails are forwarded to an external address AND spam mail is stored in the Junk folder only. This is, what I want BUT:

the clean mails are stored in the inbox too. I don’t want it stored in the inbox. How can I disable this without disabling the storing of spammails in Junk folder?

To be clear: I WANT spammails stored in the Junk folder and all other mails ONLY forwarded to an external address (without local storing).

OK it does not work. When I set it to forwarding mails, ALL mails, including those in the Junk folder are forwarded. I want only the Inbox mails being forwarded, not the Junk.