I used the Stealth Publish plugin (https://wordpress.org/plugins/stealth-publish/) and after a while I noticed that I dont send any trackbacks to outside blogs even with the options unchecked. Than I deactivated the plugin, no luck, its not sending anything.
I tried with all plugins disabled, no luck.
Right now I think this module did something in the settings of the server.... Hosting guys as usual have no idea.
So, what can i try?