Outbound spam control in Office 365 is at the organization level, similar to connection filters. As a result, there is only one default outbound spam preference entry; this filter applies to all mailboxes. This filter has the following two settings:
Send a copy of all suspicious outbound email messages to the following email address or addresses. This option enables you to specify the email address or addresses of administrators who will receive copies of all suspicious outbound messages. If sending to multiple addresses, separate the addresses with a semicolon
Send a notification to the following email address or addresses when a sender is blocked for sending outbound spam. This option enables you to specify the administrator email address or addresses to notify when outbound messages identified as spam are blocked. Again, use a semicolon to separate multiple addresses.