Jeff Huang:
> I found that the Return-Path is null when postfix send bounce mail.It =
> like this:
>
> Return-Path: <>
This is required by the Internet mail protocol (RFC 821, RFC 2821,
RFC 5321).
> It means that the bounce mail has no from,and some mailServer reject
> these email.
Then those servers do not correclty implement the Internet mail protocol.
However, you should not be sending lots of bounce mail at all. You
are sending SPAM back to people who did not send that SPAM at all.
Instead, you should block mail before it is received. Don't accept
mail for non-existent recipients.
Wietse
