Subscribers may post to my list, but one/some of
them are 'not authorized' to post.
Likely causes are:
- The subscriber's address has changed since they subscribed.
Review your list (see How do I find out
who is on my list?) and compare the subscribed address with the
From: address in their current mail message.
If the subscriber's address has changed, you should remove the old
subscription and add them at their current address,
since they will also not be able to unsubscribe or
change their mail settings from the new address.