[toni]

Currently these Mozilla domains are blocked in our internal networks. Not all of them are data-collecting services, but it's better to be safe than sorry:

    self-repair.mozilla.* 
    tiles.services.mozilla.* 
    tiles.*.services.mozilla.* 
    pfs.mozilla.* 
    snippets.mozilla.* 
    fxfeeds.mozilla.* 
    services.addons.mozilla.* 
    crash-stats.mozilla.* 
    *.data.mozilla.* 
    versioncheck-bg.addons.mozilla.* 
    fhr.cdn.mozilla.* 
    sendto.mozilla.* 
    push.services.mozilla.* 

The amount of stuff you must block to have a decent browser experience nowadays is simply mind boggling. Of course, Chrome or Opera are no more better.

[JoshTriplett]

Some of those sites are used by the addons service to keep addons up to date, and by blocking them you potentially prevent updates.

[toni]

You can always go to Tools -> Add-ons and mass-update all your add-ons manually at once (Click on the gear icon drop down and select "Check for Updates"). These rules will not block that.

[JoshTriplett]

Most people will not do that; they (sensibly) expect automatic updates.

[toni]

The type of privacy-conscious users/organizations who go to such a length in blocking these domains will also do the update manually or via their own internal update processes.

I'm not sure what most people do will have any relevance to the point I was trying to make.

[jakobdabo]

Check the about:networking page and prefs.js in your profile directory regularly for finding more domains to block.