[Mailman-Users] New user - Mailman question

[Charles Mikecz Vamossy]

HI, I am a new member of the list and a list administrator responsible for 
two lists.  Frankly I am struggling with some of the features and functions 
and I thought I would ask "my elders" for some guidance.

Our lists are very simple: we distribute weekly information to members 
about our organization's programs.  Our members sign themselves up 
automatically, receive a confirmation request and when they respond, they 
get a welcome letter.  Only two people (who are also the administrators) 
can send postings.  Letters sent by other members and non-members should be 
rejected automatically, with an explanation.  (They can write to our 
organization directly...)

The problem is that non-members have apparently written postings and we, 
laboring under the impression that if we do nothing, their letters will get 
deleted, did in fact do nothing - and the letters appeared on the 
list.  Apparently, we are told by the folks who run the lists for us, there 
is a "set period of quarantine", and when that expires, the letters are 
treated as approved.  This is news to us, and we are unable to find any 
reference to it in any documentation.

Can you help us and tell us where to find information on this?  Are there 
any parameters we can set differently?  Is there anyone out there with a 
similar problem and how do you handle it?

many thanks in advance

Charles