QMail and global filter

[itschemnitz]

Hi,

I've a second server only for mails. This server is doing virus and spam scanning and adds an header entry to infected mails. Now I'm looking for an option in Plesk or in QMail on my root server, for moving such marked mails for all imap-accounts in QMail to the corresponding spam-folder of the user (more precise, I'm looking for a server-wide filter in QMail). This filter script should create the spam folder for the user when it doesn't exists.
Who could help me?

Nico