Trackback, Pingback and Getting Found
First, you need to know that it isn’t YOUR blog settings that are allowing you to trackback to another blog, but rather THEIR settings. Each blog owner has the choice to allow it or not (including you).
On Wordpress, they can turn this option on or off at Dashboard | Settings | Discussion. It is the “Allow link notifications from other blogs (pingbacks and trackbacks)” in the Default article settings section.Read The Rest