QUOTE(cppgenius @ Sep 8 2008, 05:48 PM)

But is it possible for the spammer to forge a Received entry at that level in the header, because at that stage the e-mail already reached the ISP of the complainant in the U.S.
In general, unless someone wants to enlighten me on this point, the spammer can put in as many bogus Received lines as he likes BEFORE he transmits the mail, but once he hands off the mail to a host not under his control, he no longer has any access to tamper with the headers. The forged lines really aren't Recieved lines at all, no more than a fake passport is really a passport. They are just "creative writing" that happens to look like mail headers.
The usual procedure in scanning a header is to start from the top, and work your way down until you reach an entry that doesn't make sense. The from-host of one line should be the same name as the by-host on the line beneath it, if you find otherwise then you may have hit the point at which the forgery began. We can't always be absolutely sure, but in 95% or better of the cases I've tried, this type of analysis leads me to the source of the mail.
Here's my casual run-through of this header:
- The first line shows that ibbsonline got the message from broadbandsupport.net. The HELO given by broadbandsupport does resolve to the indicated address, although the address does not resolve back to the name. This is poor form, but maybe not a shooting offense.
- If this spam had been sent to you, you would probably recognize ibbsonline as being part of your normal mail service. If the recipient had gone through the SpamCop mail host configuration process, then broadbandsupport might have a clean bill of health as well. We will wait until the next line to pass judgement on broadbandsupport.
- On the next line down, broadbandsupport.net gets the mail from pangkor.motour.gov.my. As I noted, the HELO name does point to the given address, although again it does not work in reverse.
- On the next line, pangkor.motour.gov.my gets the mail from localhost. The "loopback" address (127.0.0.0) is given as the address for localhost. At this point, I would give up because localhost/127.0.0.0 is not something I can track down. That's why I concluded that the source was pangkor.motour.gov.my.
- Continuing on just for fun, the next line shows the same thing: pangkor.motour.gov.my gets the mail from localhost. This is a malformed header (otherwise it would be showing us who localhost got the mail from).
- The last line shows the same thing yet again. This is really goofy.
- I note that there is a block of X-headers after the third line, and they smell a bit funny (negative spam score, incomplete X-Virus-Scanned info). This would tend to reinforce my conjecture that the forgery started at that point.
I can't guess as to what path this message may have taken before it was sent by pangkor.motour.gov.my, but I have a fair degree of confidence that it did pass through this server. I am far more certain that the mail passed through broadbandsupport, and this may be an open relay, but I have no way to tell from here. The domain motour.gov.my does not appear to have SPF records, so I can't tell whether pangkor is a bona-fide outgoing mail server.
As far as the X-headers are concerned, I generally treat X-headers as being possibly interesting to read, but not proving anything one way or another. The "X" stands for "eXperimental" of course, and you use their information at your own risk.
This page on my website explains this procedure in more detail, perhaps you might find it useful:
http://www.rickconner.net/spamweb/pop-find-mail-host.html-- rick