Spam filtering fails for e-mail aliases

[yabado]

I am having the same problem found here in the KB...

http://kb.sp.parallels.com/en/111762

Symptoms
When receiving spam in a mailbox with a mail alias, spam that was sent to the mailbox will be correctly placed in the SPAM folder. However, spam sent to the alias will appear in the inbox, when it should be placed in the SPAM folder as well.

Furthermore, after inspecting the alias email headers, Spamassassin does not even touch these messages.

I am using latest version of Plesk 12 and am on Cloudlinux OS ( Centos ).

The resolution in the article only has solutions for Ubuntu.

Is anyone else having this issue?