--On Friday, January 23, 2009 14:32 -0700 David MacQuigg
I have yet to see any sensible use-case that would be
complicated by a requirement that the HELO/EHLO name end in a
registered, verifiable domain name.
Today, under 5321, EHLO clearly requires a fully-qualified
domain name that can be resolved unless the host doesn't know
its name and has to use an IP address, a situation that the spec
doesn't encourage. My reading of 5321 (but not necessarily 821)
says that HELO does too.
So what are you asking for that isn't there already?
Elimination of the IP address literal option? Some criteria for
"verifiable" that would presumably lie well outside the scope of
Do keep in mind that we know from experience that the bad guys
have absolutely no trouble obtaining perfectly valid domain