[ILUG-BOM] Q on fundas

Philip S Tellis philip.tellis@[EMAIL-PROTECTED]
Tue Oct 9 12:51:03 IST 2001

On Mon, 8 Oct 2001, Sandeep Periwal wrote:

> When sending emails, I have set my Linux Box to represent as
> "aaaaaa.com", which is a non existing domain. Now if I send an email
> from this linux box [aaaaaa.com domian] to some yahoo.com address
> which does not exist, say bbbbb at yahoo.com, then the Yahoo SMTP will
> bounce this mail back. The Yahoo SMTP will bouce the mail back to
> the SMTP of aaaaaa.com [ which does not exist ]. So what will happen

I'm assuming that yahoo blocks non-existent domains from sending mail.

It depends on how the mail is being sent.  If your smtp server connects
directly to yahoo's smtp server then the mail will be rejected before it
even leaves your machine.  Not because the destination account does not
exist, but because the source domain does not exist.

If you send your mail through a smart host, then it depends on how your
smart host is configured.  If it is configured to block non-existent
domains, then same problem.  If non-existent domains are allowed to
connect, then the mail will go to your smart host, but will be rejected
from yahoo.

Now, assuming that the mail has in fact managed to get out of your
system, and got somewhere - either your smart host, or yahoo.  It will
bounce for one of the two reasons.  Where does it bounce to?

The server that is bouncing the mail will basically do a MX lookup for
the destination domain (aaaaa.com), but will not find it.  It will
realise that it cannot return the mail, so will check what it is
configured to do in such cases.  In most cases, it would be configured
to bounce the mail to a postmaster in its own domain, and this it what
it does.

Does that answer your question?


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using ad hoc techniques.
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