Spam and ISPs

Jun 28, 2007 2 Replies
N

Dear Group,



I have made an interesting observation and would appreciate your comments.



I receive spam e-mail which is NOT addresses to me. The first three letters in the e-mail address of the spam are identical to the first three letters of my regular e-mail ddress, the remainder is not.



Example: my real address might be: abcd....@, but the address under which the spam is delivered might be abcxy....@



I have tried to mail to abcxy....@ and the mail does not reach me, nor is a message about undeliverabiltiy returned to me.



I find this curious. !.) How is it that an ISP will allow mail under an address which is not mine to pass?



2.) Why is it that I can't send and receive mail using this address?
3.) Why is it that no "undeliverable" message is returned?

Thank you for any explanations. GR.


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S

Carbon-Copy or Blind-Carbon-Copy?

Because it's not yours?

Because you receive the mail?

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A

The spam mail wasn't sent to the mail address in the To: header. That has to do with how e-mail works. I'll demonstrate by manually sending an e-mail to myself:

cobalt@chrome:~ $ telnet mail.planetcobalt.net 25 Trying 217.10.9.49... Connected to mail.planetcobalt.net. Escape character is '^]'.

220 mail.planetcobalt.net ESMTP Postfix HELO planetcobalt.net 250 mail.planetcobalt.net MAIL FROM: snipped-for-privacy@planetcobalt.net 250 2.1.0 Ok RCPT TO: snipped-for-privacy@planetcobalt.net 250 2.1.5 Ok DATA 354 End data with . From: snipped-for-privacy@whitehouse.gov To: snipped-for-privacy@example.com Subject: example

Example .

250 2.0.0 Ok: queued as 6C7403C00084 QUIT 221 2.0.0 Bye Connection closed by foreign host. cobalt@chrome:~ $ _

The above SMTP chat results in the following mail in my inbox:

----88----

As you can see the From: and To: headers just show arbitrary addresses I entered there ( snipped-for-privacy@example.com isn't even valid as per RFC 2606). The real address the mail was sent to is snipped-for-privacy@planetcobalt.net, which you can see in the X-Original-To: and Delivered-To: headers that were added by my mail server.

Anyway, this topic is by no means security-related. The appropriate group for this kind of question would be news.admin.net-abuse.mail (where this question might be an FAQ).

cu

59cobalt
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