My email servers output gets accepted by most all others so this isn't a big issue. However there is one server that gives me this rejection: Code: <email@example.com>: host mail15.mydomainwebhost.com[x.x.x.45] said: 550 See http://firstname.lastname@example.org&ip=x.x.x.150&receiver=x.x.x.45 (#5.7.1) (in reply to MAIL FROM command) Now my mail server that send out the email@example.com is on IP address x.x.x.148, not x.x.x.150. The only thing on x.x.x.150 is dns for ns2.mine.com which is the reverse dns name. The remote server is wanting to see my mail server as reverse dns but that is on x.x.x.148. So my setup is working 99.99% percent but any ideas why not with this one remote server? I'm thinking they are configured badly at mail15.mydomainwebhost.com.