Mark wrote: > >> Received: from mail.apache.org (hermes.apache.org [209.237.227.199]) >> >> Here we're lucky and the domain is at least the same, but there is no >> need for that to even happen. Especially then you think about virtual >> hosting. >> > > Yes, a very bad idea. And a mite on the side of RFC ignorance. :) > > "mail.apache.org" is the HELO name, supplied by the connecting client. > This FQDN has to resolve to the connecting IP address, 209.237.227.199, > which is does.
Actually, according to RFC 2821 section 4.1.1.1 the EHLO/HELO string doesn't have to be a FQDN at all, much less resolve to 209.237.227.199. According to that RFC, if there's no meaningful domain name you SHOULD use an address literal.. but even that that is not a MUST.
