Thanks tha_watcha, I think I have this set up correctly.
I have both the Administrator Access and Moderator Access Masks set to have 'Moderator Access'. My user is assigned to both the Administrator and Moderator roles. In the forum configuration I have the roles mapped to the appropriate administrator and moderator access masks. Still no emails.
Just to clarify; where the site mentions 'group', this is really a 'role'?
How can I assign individual users to an Access Mask? I thought it had to be done via a role. I guess there can be only one user assigned a role.