Catch and block links that were triggered by an external application like a desktop mail client

Dear mozilla community,

I’m searching for a possibility to catch and block with my firefox extension the loading of a link, which was triggered / opened by an external application. I’ve tried already with multiple API-Hooks:

runtime.onStartup.addListener
webNavigation.onCommitted.addListener
webNavigation.onCommitted.addListener
webNavigation.onBeforeNavigate.addListener

Sadly I’m not able to catch all links that are coming from external applications. There are still some options when the link wasn’t catched. Also using the API-Calls mentioned above, I’m not able to block the webRequest before it executes. In the background the webRequest was executed before these API-Calls.

What I need:
A hook which catches external link openings, wich blocks the webRequest, does some analytics and decides if it will start the webRequest or block it.

Thank you for your help & greetings,
Vivian