just to share here and wondering if any one of you facing the same problem we get alot of user complaint of can't getting email sent by yahoo sender and with carefully checked, it is blacklisted by spamcop and so happen we are using that as one of the RBL source a quick check here you will notice there are tons of 106.10 yahoo IPs are blacklisted as well http://www.spamcop.net/w3m?action=checkblock&ip=106.10.151.182 anyone want to share their view and action advising their email user ?