Filter email by subject

[Massimo_Dalla_Nora]

Hi,
I need to filter email at the server level and not of the client, because I have an external spam filter server.

Scenario:
An external sender send an email to my domain.
My domain is hosted in plesk but the emails are filter by an external spam filter.
The external spam filter send in my (plesk) mailbox a email notification.
This email notification have a subjetc like this: **** SPAM IN **** Subject...
This notification arrives in INBOX folder.

Question:
Is possible modify the plesk configuration to filter this notification and put in INBOX.Spam folder?
I don't want to switch on server-side spam because I've just an external service.
I would modify the configuration if is possible like plesk_virtual or like maildrop.

Thanks in advance