> But when a subscriber send to the list, he receive something like
> Your message has been submitted to the moderator of the list...
 
You can change this message by creating a MAILTPL file for that
list.
 
> And as a list maintainer, I got:
> The enclosed message, found in the LISTSERV mailbox and shown under the spool
> ID 0261 in the  system log, has been identified as  a possible delivery error
> notice for the following reason: mail origin seems to be a LISTSERV server.
> ......
> (The original post from the subscriber)
 
If you're getting *this* message for a posting to a list, there's
something else wrong. Do you have listserv@yoursite as the editor
of the list?
 
> How do I set it up so that subscriber get a "This list does not
> accept user posting"
> kind of message and the message is automatically discarded
> without sending any message
> to list moderator?
 
See above re: MAILTPL, and set the first editor to point to a
'black-hole' alias that is essentially '|/bin/cat /dev/null'. The
attempted posting is sent to the first editor in the list, so
list the 'black-hole' alias as the first editor. MAILTPL
customization is described in chapter 9 of the List Owner's
Guide.