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Re: People forging their From: addresses

  • To: Nate Waddoups < >
  • From: Freek de Kruijf < >
  • Date: Wed, 30 Sep 1998 11:35:26 +0200
  • Organization: Rekencentrum TU Delft

Nate Waddoups wrote:
> ...
> I cannot help but wonder why spammers choose to use legitimate domain
> names when they forge "From" headers.  What good could it possibly do
> them, as opposed to just using something that doesn't exist?
> Puzzling.

A lot of e-mail systems check the from-address for existance. If this
address does not exist the message is not accepted.

Unfortunately a lot of these e-mail systems use the wrong return code.
When the domain does not exist they should permanently reject the
message; in SMTP-terms an 500 error code should be given, however often
a 400 error code is given. This 400 error code should only be given in
case the DNS system is not responding on the request.

Freek de Kruijf        e-mail: F.deKruijf@localhost
Rekencentrum TU Delft  tel. 015 278 3226  fax  015 2783787
Postbus 354            M. de Ruyterweg 10-12
2600 AJ Delft          2628 BA Delft

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