outbound trackbacks not working

I was having a problem with my cpanel the other day and the host made some changes on the server (I think it was the htaccess) – ever since then outbound trackbacks have not worked – I have several waiting in the cue right now.

What are the changes that could have been made that could be causing this problem? I could use help understanding the proper htaccess and server settings from a host’s perspective to do outbound trackbacks so that I can assist them in correcting the issue. Thank you.