Marcio,
If I have a moderated group (that is, a group like this one for
example), is there a way of making sure that a person will be able to
bypass this moderation (that is, their messages will be automatically
aproved)?
Yes. In his/her membership page change the Posting Privileges setting to "Override: not moderated".
It is "under construction", but see also:
/g/GroupManagersForum/wiki/Message-ModerationShal
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