Adam Stephens wrote:
>
> Similarly, section 3.6 requires all domain names used in SMTP
> transactions to be 'resolvable, fully-qualified, domain names'.
Just quoting section 3.6 of RFC2821:
- 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.
How many people here do filtering based on "resolvability" of the HELO
argument? I just wonder, I think this should be very effective at
filtering spam, but would reject way too much ham.
