[SC-Help] Re: Spamcop treats MX differently depending on where it appears in chain

[Blammo]

On 02 Apr 2005 You have no need to know entered spamcop.help and left 
news:pan.2005.04.02.13.46.35.360438 at fl.net.invalid:

> The spammer connected to one of the ISP's MXs. The name the MX put in the
> received line is a valid name for the box.
> 

You didn't actually supply this line...

Received: from spammer.name (spammer.PTR [spammer.IP]) bla
  bla by mx.name

This is the line the incoming MX writes, this is the line Spamcop has to 
find.

> If you do the forward lookup on that name you get the same IP as one of
> the MXs.
> 

Uhm, which MX, where?

> If you then reverse lookup that address you get the name in the received
> line. This is not a name that appears in an MX record. (If there were PTR
> records for each A record this would not happen.)
> 

No, no, no, it don't need to BE a mx record, it needs to HAVE a mx record, 
who's IP matches. Domains have MX records, IPs don't, that's actually part 
of a bigger problem.
The problem I see is that the name in the PTR record has no A record. 
Spamcop can't find any A or MX records for the PTR name. Depending on what 
they are using for DNS, it may be hard to keep the PTR and A records 
synched up, so this could be a temporary problem.

>> In your first example, why doesn't isp-other-name.mx match 4dmail.co.uk?
>>
> Because isp-other-name.mx is one of the MXs for the other name by which
> my ISP is known. I said that in one of the comments you snipped. 
> 4dmail.co.uk was the source of that mail.

The MX name has nothing to do with it, we only see two things here, the IP 
and the name the server writes into the header, which doesn't match for 
some odd reason. Your answer doesn't explain why they don't match.
You haven't explained why "by isp-other-name.mx (Postfix)" claims it's name 
is "4dmail.co.uk", that would mean Postfix is not configured properly.

-- 
| Ric