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RE: Backward compatibility with deployed SPF records (and choice of domain)

2004-06-27 14:40:40

On Friday, June 25, 2004 10:28 PM, Greg Connor wrote:

1. Placement of TXT records.

    The co-chairs find that the working group has not come 
to consensus on
    the use of a record prefix vs [unprefixed] TXT records


I think I would agree with Roy that allowing MARID-compliant 
MTAs to check 
the unprefixed name is desirable.

In other words, if MARID-Brand LMAP works substantially similar to 
SPF-Brand, let's go ahead and use their data.

One concern here is that we would want the semantics to be 
similar enough 
to not upset or surprise anyone who isn't expecting their 
data to be used a 
slightly different way, but I think we are able to do that.  (That 
certainly was the intent of the SenderID merged proposal)

In a straight race, I would probably root for the 
non-prefixed records to 
win, simply because the underscore might scare and confuse 
people (it was 
removed from early versions of SPF for mostly that reason).  I do 
understand the issue that the prefix is intended to address, 
but I don't 
think the research we have shows it is anything to worry 
about.  I think 
most users will not have TXT records of any other type, and 
of those that 
do, the records will mostly be small enough to coexist 
peacefully.  I don't 
have a strong preference in this area, except that backward 
compatibility 
would allow MARID to harness and redirect the momentum SPF 
has built up. 
(Of course we will be going through the process of getting 
our own RR so we 
will eventually have an escape plan)

Does anyone have a strong objection to using unprefixed txt records?


I think this is just going to invite problems down the road.  Although
data may correctly show that TXT records are not used frequently today,
that's no guarantee of future use.  Likewise we cannot predict the
length of data stored in future TXT records.  Multiple TXT records could
push responses over the 512 byte threshhold. 

Segregating MARID records into their own subdomain addresses these
issues.  

We advocate the use of an underscore as a way to celarly distinguish
this record from a hostname, but we're not married to it.


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