What, if any, changes were made to the comment notification system in 2.1? I have had no luck in receiving my comment notifications on two of my sites, but a third site (with the same host)works properly. I've checked my htaccess, themes, plugins, and everything else I could think of. If I had better knowledge of what to tell my host, they could help me determine if it's a hosting issue since I'm getting a 550 error now. Thanks.