On 11 Jun 2002, at 9:06, Randy Klumph wrote:

>One of my users accounts is generating the following error
>
> > Last error: SMTP; 553 sorry, your envelope sender has been denied (#5.7.1)
>
>I had him send it to his ISP but they do not understand the error message
>and will be contacting me for clarification. Can someone help me understand
>the problem so that I can inform the ISP and resolve the issue. Thanks

From RFC1893... the leading 5 means it's a fatal (to delivery) error:

 X.7.1   Delivery not authorized, message refused

    The sender is not authorized to send to the destination.
    This can be the result of per-host or per-recipient
    filtering.  This memo does not discuss the merits of any
    such filtering, but provides a mechanism to report such.
    This is useful only as a permanent error.

The ISP turned on a filter to block mail, but doesn't understand the
message it puts out to confirm that it has done so.  Pretty much what
one has to come to expect of todays knuckles-and-knowhow ISP's.  ;-(

                                                 -Kary