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@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?
Philip