On 2010-07-21 Aniruddha wrote: > When somebody emails to a non-existing e-mail address postfix bounces these > by default with a "Recipient address rejected: User unknown in local > recipient" error.
No. Postfix REJECTS them with a "User unknown in local recipient table" error. Rejection takes place during the SMTP dialog, meaning that the message will go back to the sending SMTP client. A bounce would be generated when an MTA first accepts a message for delivery and *then* decides not to. In which case the NDN goes back to the (envelope) From address, which in case of spam mails is usually spoofed. This is what is known as "backscatter". > I wonder what the appropriate behavior is. To discard emails for > unknow, users, forward them to another address or bounce them? The appropriate behavior is to reject messages you know you can't deliver, bounce messages you find yourself unable to deliver after accepting them, and to make sure the latter does not happen much. > What about backscatter? Doesn't bouncing generate a lot of > backscatter? Bouncing does. Rejecting doesn't. Regards Ansgar Wiechers -- "Abstractions save us time working, but they don't save us time learning." --Joel Spolsky
