andyjakubczak To manage moderation notifications when messages are not approved you can use Set-mailbox cmdlet- https://docs.microsoft.com/en-us/powershell/module/exchange/set-mailbox?view=exchange-ps
-SendModerationNotifications
The SendModerationNotifications parameter specifies when moderation notification messages are sent. Valid values are:
- Always: Notify all senders when their messages aren't approved. This is the default value.
- Internal: Notify senders in the organization when their messages aren't approved.
- Never: Don't notify anyone when a message isn't approved.
This parameter is only meaningful when moderation is enabled (the ModerationEnabled parameter has the value $true).