Alert Mail for specific Web Filter Categories.

Hi community,

I'm trying to enable alert Mail only for specific category (in my case pornography), if i'm looking to alert setting i can set only for WebFilter (So all WebFilter matches will geenrate a Mail alert but i wan't to avoid alert mail related to Social Networking site for example.

I can set also alert mail for severity but it's not useful because  log weight it's different  than severity.

We don't have FortiAnalyzer so we can't generate report to monitoring who is using pornography sites.

So how i can generate a alert mail only for a specific category of webfilter such as Pornography?

Thank to all.

Stefano