When migrating a large message in On Demand Migration for Email (ODME) there is an error of Could not save' and the email is not copied to the target mailbox.
Could not save: "" Subject: <subject of the message> Message ID: Path: Sent Items Received Date: 1/1/2016 2:01:23 PM From: "User Name" To: Other User
On the Options tab of the migration plan, under Advanced, change the Maximum message size to a value between 1 and 2047 MB. Then change the Office 365 or Exchange server to allow the message to be received.
See KB 223012 for steps to increase the limits in Exchange.