whats the deal with moderators

[Thomas Beckett]

When I send emails to the ubuntu users list, some of them get stopped
for moderator approval. It is not all of them, jsut some - even though
they are sent from the same account as some that get through
instantly.
I just thought - the one that got stopped just had the users lis in
the cc field ratehr than the main To field will this be the reason
they get stopped?

Tom