Doing the opposite: Blocking certain html from being served possible?

Hi All,

We host websites and sometimes bad actors create phishing sites during their trial period. Specificity fake Outlook webmail login pages where they harvest email/passworks. We shut they down as soon as possible but still it not instant.

They create a form on the web page and there’s a “post” method to a 3rd party service (

Is there anything HAProxy or other that can block traffic going out that contains a spefic string of data or html code. Something like if server is sending out a html page with the url block traffic.

This sounds like something the complete opposite of what HAProxy is designed for. We’re currently using HAProxy + Let’s Encrypt for ssl and load balancing our backend server.

Any help is appreciated.