I've just realised that I don't understand something clearly. I have this top header in a mail;
Received: from instantinfo.com (unknown [74.10.219.114]) Received: from ipnet5-host235.subictel.com (unknown [210.14.36.235]) and even some like this; Received: from MKISHQCX ([118.76.7.122]) Normally I see the same host value before and after the parentheses, and I've only just spotted this and realised I'm not truly clear on what I'm looking at here. Does this translate to? 'helo' client hostname (rdns client hostname[connecting ip]) Or am I missing a beat on a core concept here? TIA Steve