[AusNOG] [SHAME] spamrats.com

Lloyd Wood lloyd.wood at yahoo.co.uk
Thu Jan 10 22:02:35 EST 2013


And, given this discussion, a trifle ironic, no?

Sorry, we were unable to deliver your message to the following address.

<noel.butler at ausics.net>:
Remote host said: 554 5.7.1 <nm3-vm1.bullet.mail.sg3.yahoo.com[106.10.148.112]>: Client host rejected: This network is currently not accepting Email from Yahoo [RCPT_TO]

On 10 Jan 2013, at 21:58, Lloyd Wood <lloyd.wood at yahoo.co.uk> wrote:

> MUST and SHOULD are defined in the later RFC2119.
> 
> RFC793 doesn't use them either.
> 
> And RFC2119 and 1912 are on the legacy RFC stream....
> 
> 
>>> 
>>> 
>>> RFC 1912, Section 2.1 says every Internet-reachable host should have a name
>>> and "Make sure your PTR and A records match" and "For every IP address,
>>> there should be matching PTR record in the in-addr.arpa domain"
>>> 
>>> its DNS 101
>> 
>> Note that it is not a *MUST* requirement, nor even a *SHOULD*.
>> 
>> And, frankly, _depending_ upon PTR records in 2013 is just plain daft.
>> 
>> % host -t mx gmail.com
>> gmail.com mail is handled by 30 alt3.gmail-smtp-in.l.google.com.
>> gmail.com mail is handled by 40 alt4.gmail-smtp-in.l.google.com.
>> gmail.com mail is handled by 20 alt2.gmail-smtp-in.l.google.com.
>> gmail.com mail is handled by 5 gmail-smtp-in.l.google.com.
>> gmail.com mail is handled by 10 alt1.gmail-smtp-in.l.google.com.
>> 
>> % host gmail-smtp-in.l.google.com.
>> gmail-smtp-in.l.google.com has address 173.194.70.26
>> gmail-smtp-in.l.google.com has IPv6 address 2a00:1450:4001:c02::1b
>> 
>> % host 173.194.70.26
>> 26.70.194.173.in-addr.arpa domain name pointer fa-in-f26.1e100.net.
>> 
>> % host 2a00:1450:4001:c02::1b
>> b.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.c.0.1.0.0.4.0.5.4.1.0.0.a.2.ip6.arpa
>> domain name pointer fa-in-x1b.1e100.net.
>> 
>> The lack, or mismatch, between advertised name and PTR records should
>> just be used as a signal to a reputation service.
>> 
>> A recent post from someone who works in this area (disclosure; I don't
>> use their service at this time) covers the kinds of signals you'd
>> generally expect to us.
>> 
>> http://rolandturner.com/2012/12/14/a-defensive-strategy-for-accepting-email-over-ipv6
>> 
>> I realise that this doesn't help the OP but I just wanted to ensure
>> that people know that PTR records are a defining anti-spam mechanism
>> are very outdated.
>> 
>> Regards,
>> Anand
>> 
>> -- 
>> “Don’t be sad because it’s over. Smile because it happened.” – Dr. Seuss
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