We have set up an IMAIL list of all of our membership (540 members) and have enabled the posters list.  We have entered a few people who are authorized to send email to this list as our Posters.  We would like anyone on the posters list to have to enter a password to send to the list for security reasons.   The list had been working fine without a password until over Christmas and someone spoofed an address book and sent out an email to our list which was not an authorized poster.  How does one do that?  Is there a way for us to set up this list to require a password?  HELP! 

Thanks,

Deb