An open list is one that anyone can freely join and exchange messages with the list address.

  > All messages are distributed to every other member
  > It is effectively like a bulletin board
  > Example of use: Product self-help group
 

A self-managing list is one to which only the list administrator can distribute messages, but anyone can freely join or leave.  

  > Messages appear to be from your address
  > Replies are returned directly to your address
  > Example of use: Product or Service Alert distribution

Ideal for Permission Marketing or 'push marketing' campaigns