spf-discuss
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Re: SPF is not usable as legal measure against spammers.

2004-07-16 07:32:50
administrator(_at_)yellowhead(_dot_)com writes:

That's interesting, because it is a very common practice these days to
service many domains from one IP address (we currently service 10 virtual
email domains from one server). You can publish multiple PTR records, but
unfortunately there are many programs out there that only look at the first
one. Reliably matching up the PTR to the "A" record is virtually impossible.

That is why SPF requires the PTR record to match *one* (any) of the A
records. So there must be an A record for the name returned by the
PTR record and that A record must resolve to the IP address being
looked up.