I understand and appreciate the function of blocklists like SpamCop and I make use of them on my own email server. I realize that the inconvenience caused is part of an imperfect system but hopefully it generates some positive change. My problem is that an important client on my mail server is suddenly experiencing blocks of his email sent from SBCGlobal (which apparently now uses Yahoo mail) when he tries to send email to his office (using accounts on my server) from home. The servers in question are Yahoo's and the latest one is 126.96.36.199 . I believe he has been using this setup for years but has never complained about blocks until a couple of days ago. The reports make it clear that SC has received lots of spam from these servers and many delisting requests. Since the servers cycle I thought it would go away quickly and so I whitelisted a couple of them temporarily. Unfortunately it still goes on. My real question is two part. First, is there something new happening with spam activity with Yahoo causing more blocks? And second, depending on the answer to the former, is there a reasonable explanation that I can relay to the client -- possibly with some hope? I realize you suggest changing email accounts and I would be with you, but this is a very little "c" conservative company and that won't happen. I can't stop using SpamCop without increasing the flood of spam, so I'm asking for suggestions. I realize I'm probably asking for an answer that can't be given, but maybe others have found a good way to relay this stuff to clients without trying to give them a course on how it all works. Thanks.