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Re: PTR lookups in SPF

2004-07-19 08:02:44
Andriy G. Tereshchenko wrote:
PTR data is not trusted source of information. RIPE/ARIN/APNIC/LACNIC whois are 
trusted.
I do not care if IP named  
"We.Deliver.Spam.To.Your.MailBox.24hours.7days.a.week.Using.Inter.Net.cn" and 
have valid A record
for this name.
Anyway I will use trusted source to get contact information about netblock 
owners.

Unfortunately the output of whois servers is well-nigh impossible to parse in a reliable, automated and useful fashion due to the enormous variation in data formats of the various registries. Hence whois data is wholly unsuitable for playing any part in the decision whether or not to accept a given mail item when it arrives.

I will never use names of domains/PTR data to block spam - it's trivial to 
reply on PTR requests using random (but still valid
for A verification) DNS names.

But not for A verification for any specific domain name you might want to forge. The choice is limited only to domain names within your control and those with A records already pointing to the right address.

Paul.


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