At 10:02 06/12/2004 Saturday, John Mack wrote:
 >Last error: 5.1.1 550 5.7.1 Relaying not permitted
 >
 >for over 100 susbcribers to my listserv.
 >
 >Never having gotten this error before with so many susbcribers, I am
 >concerned that something is
 >awry. I have not done anything to change my list (no header changes that
 >is) and the accounts
 >sending this error back to listserv are varied and not from new subscribers.
 >
 >Any ideas? SHould I be concerned?


YES ... you should be concerned, as I am to..  This occurred yesterday
for one of our daily distributions from a moderated list, where there
moderator's email address has just changed to an anti-spam host.  Same
symptoms as yours.  Here is what I wrote her:


This number of bounces is highly [!] unusual.   I just checked the first
three -- they ARE subscribed so I don't think that they represent a
spoofed distribution.

According to RFC1893:



Security or Policy Status

        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.


My guess? Your new a/spam mailbox sender.
[...]

It also means that these individuals (or their ISPs) had white listed
your old email address and NOT your new one [so far].