Had a client who has contacted me to tell me that they are having trouble emailing people , as they get a bounce back to say it has been blacklisted. I have checked their IP, and indeed it is blacklisted on http://mxtoolbox.com/ with 6 different RBLs. The annoying thing is that they rang slingshot and told them about the problem, the helpdesk said that they would need to contact the person they are sending it to. But the blacklist is on the RBL, so it would affect most people they send emails to, and only slingshot can get themselves removed from the RBL. So what is your process for getting blacklisting removed for your IP's when they have been blacklisted in the RBL? Shouldn't you be doing this?