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.