An SMTP HELO/EHLO is used within the SMTP transaction to identify the sending mail server. It is BCP (best common practice) for any ISP or organization operating a mail server on the Internet (and in fact defined by RFC 2821, page 29, section 4.1.1.1, read in conjunction with the definition of "Domains" outlined in section 3.6, page 22 and section 4.1.2, page 37) that when an SMTP transaction is begun, the client (sending mail server) is to identify itself using HELO/EHLO followed by a fully qualified domain (hostname) or address literal. A domain is defined as being a combination of letters or digits, followed by a dot "." and a combination of more letters or digits. For the purpose of RFC2821, it is defined that a domain is a fully qualified and resolvable name. An address literal is an IP address enclosed in square braces [x.y.z]. It is policy of LightHouse Hosting to reject any and all attempts to deliver mail when there is...