BypassNestedModerationEnabled

New-DistributionGroup -Name Forum2011 -ModerationEnabled $True -ModeratedBy "Windy Phillips" -BypassNestedModerationEnabled $True
New-DistributionGroup -Name CEO-2011 -ModerationEnabled $True -ModeratedBy "John" -BypassNestedModerationEnabled $false
Set-DistributionGroup -Identity "Forum2011" -BypassModerationFromSendersOrMembers "Administrator"
"George Allistair","Algo Clinton","CEO-2011" | Add-DistributionGroupMember -Identity "Forum2011"
Add-DistributionGroupMember -Identity "CEO-2011" -Member "Scott Culp"

Test:

Jim Patterson sends a message to Forum11.

After Windy Phillips approves it, Scott Culp receives the message without the John's approval.

Set-DistributionGroup "Forum2011" -BypassNestedModerationEnabled $false

test:

Jim Patterson sends a message to Forum11.

After Windy Phillips' approval, George Allistair receives the message but not Scott Culp who is a member of the nested group.

The moderator John of CEO-2011 has to approve it.

New-DynamicDistributionGroup -Name DForum2011 -ModerationEnabled $True -ModeratedBy "Windy Phillips" -ConditionalCompany 'vanarts' -includedRecipients 'mailboxusers'

There is no BypassNestedModerationEnabled parameter for a Dynamic Distribution Group.

If the moderator doesn't respond to the message within five days, the Information Assistant will delete the message from the arbitration mailbox and notify the sender that their message has expired.

The arbitration mailbox is used to store the original message that's awaiting approval. By default, one arbitration mailbox is created for moderated transport during setup. It's used for all moderated recipients. You can add additional arbitration mailboxes for load balancing purposes. If you're using multiple arbitration mailboxes, you need to specify which mailbox to use for each moderated recipient.

When messages sent to the moderated and non-moderated recipients, the transport service bifurcates the message and deliver a copy immediately to the non-moderated recipients. A separated copy is delivered to the arbitration mailbox to await attention from a moderator.

Moderated Mailbox

Set-mailbox -Identity "John" -ModeratedBy "Administrator" -ModerationEnabled $True -BypassModerationFromSendersOrMembers "George Allistair" -MailTip "Messages sent to John are reviewed by Administrator before delivery."

Mail-enabled contact can be moderated, too.

New-MailContact -Name "Kaiming" -ExternalEmailAddress "Kmliao@hotmail.com" -ModeratedBy administrator -ModerationEnabled $true