On 7/17/11 9:37 PM, Stephen Harris wrote:
> On Sun, Jul 17, 2011 at 09:07:38PM -0500, Les Mikesell wrote:
>> There is no requirement for the greeting name to match any IP, and isn't likely
>
> RFC2821 says:
> - The domain name given in the EHLO command MUST BE either a primary
> host name (a domain name that resolves to an A RR) or, if the host
> has no name, an address literal as described in section 4.1.1.1.
>
> So, pretty much, HELO or EHLO greeting _must_ match to an IP.
>
> (RFC821 actually wanted the HELO to match the connecting host, but
> 2821 just says it must be an A record or an address literal).
That's a long way for saying it MUST be the name of that particular host (which
might be one of many in a cluster sharing a name) or that it MUST use the name
of the interface that it happens to use for a particular connection, or that its
own interface IP MUST be what connects to the target with no NAT involved.
Saying any of those things would make it very difficult for mail services to scale.
--
Les Mikesell
lesmikesell at gmail.com'