Re: Last Call: On-Demand Mail Relay (ODMR) to Proposed Standard

[Randall Gellens <randy@xxxxxxxxxxxx>]

ODMR is a profile of SMTP, and as such generally uses the SMTP rule 
for <domain>.  The only reason for including the BNF in this draft, 
instead of a reference to 821, is to prohibit the use of IP addresses 
in lieu of domains.  SMTP needs to permit this, but ODMR does not. 
It makes no sense to use IP addresses as domains in ODMR, since the 
intent is to permit a customer to collect mail for established and 
known domains.

My understanding is that Graham is correct; SMTP does limit domains 
from what DNS itself is capable of using.  ODMR further constrains 
domains to exclude dotted-decimal IP notation.