[Mailman-Users] "relaying prohibited by admin" error

[Wolfram Knipp]

hi,
  I've just completed (I think) configuring my mailman.. now, whenever I try
send a mail to a list I've created, I get returned this:

   ----- The following addresses had permanent fatal errors -----
<mylist at lists.mydomain.org>
    (reason: 550 relaying to <mylist at lists.mydomain.org> prohibited by
administrator)

   ----- Transcript of session follows -----
... while talking to m1.dnsix.com.:
>>> DATA
<<< 550 relaying to <mylist at lists.mydomain.org> prohibited by administrator
550 5.1.1 <mylist at lists.mydomain.org>... User unknown
<<< 503 Valid RCPT TO <recipient> must precede DATA

anyone can assist me with this issue?
I've done the necessary modifications to the /etc/aliases file after adding
the list, and have also run the "newaliases" command.

thanks in advance


-
Wolfram Knipp