Re: how to avoid receiving email w. sender forged to be a host in my dom

On Wed, Aug 11, 2004 at 10:52:05PM -0400, Tom wrote:
> Well, this really has nothing to do with spf, but all of my A records were 
> being ignored. After I commented out the wildcard TXT entry, everything 
> started working again. I know BIND has a bug that causes problems if the 
> last record is a TXT record, perhaps I stubbled upon another bug. I didn't 
> go through the motions of diagnoising it because I was more interested in 
> getting my DNS server back up and running.
Just curious what version of bind you are using, because I never
experienced this 'bug' you think you have found (also using bind here).
Are you sure you didn't put a typo in the zone file, which would render
the entire zone unusable?

> The real question I was asking here is what would happen if a third level 
> domain has no DNS records (assuming the MTA doesn't throw it away for that 
> first)?
>
> Example:
>
> spammer_(_at_)_fakesub(_dot_)mydomain(_dot_)org
>
> If there are no DNS records (spf or otherwise) for fakesub.mydomain.org, 
> what happens then? Are spf records for mydomain.org still ignored in this 
> case?
If a TXT lookup of _fakesub.mydomain.org (ignoring that the _ is not
allowed iirc) does not return a spf TXT, no spf will be checked.
However, if there's no dns record at all for the domain, most modern mta's
will (should?) reject anyway.

Koen

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