So gmail.com and yahoo.com have been identified on sorbs.net as SPAMers or SPAM-vertizers. Or am I reading this incorrectly? Since I have RBLs enabled, and sorbs.net is one of the RBL list maintainers, those domains get rejected?
Take a look at a recent bug report on the topic re a corrupt database at sorbs.net, which is probably the same issue you are experiencing (Bug link at top of Forum).