spf-discuss
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Re: Re: [spf-discuss] New SPF Council - was Reclassifying Sender ID and SPF as Historic

2009-01-21 11:40:46
On Wed, 21 Jan 2009, alan wrote:

several have commented with all the v1 and v2 records in place and now a v3 
on top
will add too much byteweight to the response to a query for UDP to handle 
efficiently {or at all in some cases}

this is a serious issue {was my problem with spf originally as it broke my 
standard of adding txt and rp records to most hosts
{now just rp pointing to a txt container}

so should we be considering a standard sub-zone for spf going forward?

no its simpler to fix than that
just recommend anyone doing more than 1 form of spf and/or sender-id 
remembers about the issue and divides his records(s) appropriately
like thus

domain.tld     IN SPF "v=spf1 redirect=_spf1.%{o}"
domain.tld     IN SPF "v=spf3 redirect=_spf3.%{o}"

domain.tld     IN TXT "v=spf1 redirect=_spf1.%{o}"
domain.tld     IN TXT "spf2.0/mfrom,pra  redirect=_spf2.%{o}"
domain.tld     IN TXT "v=spf3 redirect=_spf3.%{o}"

That puts all that TXT data into a UDP packet - thus the "byteweight" problem.
One suggesting that *would* help is the standard subdomain:

_spf.domain.tld IN SPF "v=spf3 ..."

-- 
              Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.


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