On Fri, 27 Jul 2012, Tony Langdon <vk3jed@gmail.com> wrote:
http://doc.coker.com.au/papers/benchmarking-mail-relays-and-forwarders/
Unfortunately you can do that and it seems to work. It probably fails in corner cases and causes extra DNS work which is a bad thing. My above paper on benchmarking DNS and mail servers is relevant. While CPU performance has increased a lot since 2006 the general principle still applies. Although admittedly systems which don't use SSD and a filesystem like ZFS are probably more likely to hit storage bottlenecks now than they were 6 years ago.
Well, you're not supposed to be able to do it, to stick to the RFCs, at least last time I had a read. :)
I'm not recommending doing it, in fact I've shown that there are performance implications that you probably don't want. But it has appeared to work in the past which is unfortunate. If it just stopped working then people would stop doing it. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/