-----Original Message-----
From: owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
[mailto:owner-spf-discuss(_at_)v2(_dot_)listbox(_dot_)com]On Behalf Of Greg
Hewgill
Sent: Wednesday, October 06, 2004 8:45 AM
To: spf-discuss(_at_)v2(_dot_)listbox(_dot_)com
Subject: Re: HELO Checking [Re: [spf-discuss] What to include...]
On Wed, Oct 06, 2004 at 01:25:08PM +1000, Raymond Neeves wrote:
HELO au01.mta.mycompany.myisp.au.com
where in this fqdn do i stop checking for SPF records?
You could walk up the DNS tree looking for SOA records. If mycompany
runs their own DNS, the first match might be an SOA for
mycompany.myisp.au.com. Otherwise, continue to remove names from the
left hand side until an SOA record is found.
Note that even if an SOA is required, there might be one for say:
example.com
And an SPF record say:
some.deep.subdomain.example.com. IN TXT "v=spf1 <shallowrule>"
But in the subdomain:
server.some.deep.subdomain.example.com
If SPF is published at:
some.deep.subdomain.example.com. IN TXT "v=spf1 <deeprule>"
But if there was no SOA for some.deep.subdomain.example.com your method would
skip over the spf
record that should have been used and end up using the SPF record for
example.com, hence you would
apply "shallowrule" instead of "deeprule".
Yes, there should be an SOA. Would you like to explain that to all the mail
admins that don't know
DNS very well? :)
Note that a simple:
server.some.deep.subdomain.example.com. IN TXT "v=spf1
redirect=some.deep.subdomain.example.com"
Solves the problems. You would need one for each of your mail servers (you
could play with
wildcards, ugh, but given there are a finite number of mail servers one has, I
wouldn't)
A decent spf record generator (e.g. the one on pobox.com) gives you the
additional needed TXT
record(s) to redirect the FQDN of your mail server to the SPF record for your
domain.
Terry Fielder
Manager Software Development and Deployment
Great Gulf Homes / Ashton Woods Homes
terry(_at_)greatgulfhomes(_dot_)com
Fax: (416) 441-9085
Greg Hewgill
http://hewgill.com
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