On Fri, 29 Jun 2001 10:54:43 -0700, Randy Klumph <[log in to unmask]> wrote:

>I received the following monitoring report on a new user. I haven't seen
>this one before. Is this a configuration problem on the user's end? Thanks
>
> > Last error: X-Notes; User zzzzzz ([log in to unmask]) not
> > listed in public Name & Address Book

Functionally it means the same as  "550 No such user".  Obviously if their mail
system is saying they don't exist, when you have good evidence that they do, it
is a problem for that mail system...