Spam filter before redirect

[sebasguay]

Hi,

I searched the forum but haven't found an answer.

Here, we have an ISP who blacklist IP address when the % of SPAMs coming from this host past a certain threshold. They don't care if it's really coming from us (which is not the case) or if we redirect only.

So, is it possible to filter (delete with SA, not just adding headers) the emails with before the redirect?

Sebas