On Aug 20, 2001 at 18:47, S. Krishnan wrote:
But if you're doing the header, wouldn't your mails show up on the recipient's system as being from the vsnl domain? Maybe I'm missing something here, but I believe that the "From" display on the recipient's client is taken from the header. Correct me if I'm wrong.
Happily.
You're making the same mistake that anyone who doesn't dabble in mail servers makes. There is a message, with headers and a body, and there is an envelope, with its own headers. This is how spammers do it: the envelope RCP TO: (yes, the envelope is set by SMTP, and most of the headers you usually see are set as part of the SMTP body, as the envelope is discarded by the final recipient MTA) points at you, and the body headers point at "foo@fake.invalid.com".
Here's how it's done (this is a simulation of an actual telnet session. No mail servers were desecrated in the making of this simulation):
$ telnet mail.localhost 25 \d\d\d Some SMTP stuff helo myself \d\d\d Moo mail from: fake@invalid.com \d\d\d Sender accepted # would be rejected if relay control was enabled rcpt to: fake2@invalid.com data From: fake3@invalid.co.uk To: satyap@vsnl.com Subject: SPAM!!
I spam you! . \d\d\d Message accepted for delivery quit
Philip is setting the mail from: header, and leaving his From: header alone.