On 2/21/2013 4:36 PM, David F. Skoll wrote:
On Thu, 21 Feb 2013 16:26:46 -0500
"Kevin A. McGrail" <kmcgr...@pccc.com> wrote:
But I do believe it's generally accepted that one of the primary
original uses for rDNS was for received headers in SMTP. I don't
think anything requires it. Someone on this list will know for sure.
My reading of RFC 5321 is that reverse-DNS is not required. Indeed,
I don't think an implementation is even obligated to put the actual
IP address of the SMTP client. The RFC says this about the FROM clause:
From-domain = "FROM" FWS Extended-Domain
Extended-Domain = Domain /
( Domain FWS "(" TCP-info ")" ) /
( address-literal FWS "(" TCP-info ")" )
By my reading, Extended-Domain doesn't have to include TCP-info; it can
just be whatever the other end said in its HELO.
So:
Received: from what-i-said-in-helo.example by foo.example.com;
Sat, 16 Mar 2002 02:22:28 -0800
is a valid received line according to my reading of the RFC. You could
complain about the quality of an implementation that produces such a line,
but not about whether it adheres to the RFC.
Unless betting for minor sums such as a beer or a happy meal, I
generally won't get into RFC compliance arguments with DFS. My reading
was similar though there are some other RFCs that extend SMTP and say
things like "if you use ESMTP, you have to add with ESMTP to the
received headers".
But as for having to add reverse DNS information, it likely would come
under an "if available, it should be added" type of clause.
regards,
KAM
