> What is the procedure for:
> 1. preventing someone from subscribing?
Change the header to sub by owner or put the person's address in the
list filter
* Filter= All,[log in to unmask]
you can use wildcards

> 2. banning someone from posting?
If you want to let the person read but never post set him to NOPOST.
For posting with approval set him REVIEW.

Now if you want to prevent subscribing AND posting the Filter= will
take care of that.  Until the person gets another address or has
someone else post for him, which he will do if he is determined.

Depends on how determined you are to keep the person out and how
determined he is to get in.  You may have to go the full security
route, sub by owner, validate, full moderation, etc.  All depends
on how far you are willing to go to keep the person out.

Douglas