Action: Messages larger than the allowed limit (currently 150 MB) will not be migrated nor delivered, and the sender will ...

Action:  Messages larger than the allowed limit (currently 150 MB) will not be migrated nor delivered, and the sender will receive a non-delivery report (NDR). Although message size limits can't be configured up, down, or on a per-user basis, administrators can create transport rules to limit the maximum size of any individual attachment. See Exchange Large Item Compliance v2.2.