Oh wise man, I'm really tired to read your answers, I do not mean, to forge mail senders address. It is possible with Outlook Express. I mean to forge header Received: content.
This is pretty simple to explain.
When your mailserver receives an E-mail, it can't trust any of the headers that the remote mailserver send it. Therefore, you can only trust headers that are added by your mailserver -- and in those headers, you can only trust information that you know is reliable.
With IMail, this means that you can trust the IP address in the top Received: header. That's it. That information is virtually impossible to forge. Any other headers are easily forgeable (except for X-UIDL: and other ones that aren't relevant, and headers added by third-party addons that may have information such as the reverse DNS entry).
"it creates whatever headers the spammers want" - first of all they must be RFC compliant, isn't it?
No, they don't. In fact, one of the ways that Declude JunkMail detects so much spam is by looking for non-RFC-compliant headers. A large percentage of spam has them.
I believe that it's possible to add any Received: lines but only from the machine where there software installed.
No. For example, if I send an E-mail to you, my mailserver will add a Received: header. Yours will add a Received: header, and leave mine in tact. So I could write a mailserver that adds a Received: header that looks like the one my mailserver adds, but has bogus information in it.
If they use open relay with Imail for example, this relay add correct header, isn it? So, at least this data will be correct to identify spam? Right?
Yes. But you have to know that it is an open relay. And, the IP address connecting to that open relay is almost certainly a dialup account or zombie, so you would need to take legal action to track down the spammer.
What do you mean under "zombies"? As I understand either hacked or infected machines where they install their software to send spam. This is not an easy task for spammer. Much better to use any legal open relay.
You do not know much about the spamming world. :)
The major spammers use zombies to send out their E-mail. Whether they do the dirty work of writing viruses and spreading them, or pay someone to do it for them, they still use zombies. Over 1/2 of all spam is sent through zombies.
-Scott
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