Message Exceeds Maximum Supported Size

Product version: 10.1

Last modified: 15 September 2020


Recovery of some contents of the Exchange Online mailbox folders fails with the following internal message error:

The message exceeds the maximum supported size.


The problem is caused by the message size limits of the Exchange Server which is 10MB by default. The Exchange Server can accept delivery of large items via Simple Mail Transfer Protocol. However, MigrationWiz migrates emails via EWS which has different size limits.


To solve this problem, you need to go to Microsoft Exchange Online and change the message limits of the mailbox that you want to recover to. This can be done the following way:

  1. Login to your Microsoft 365 account.

  2. Navigate to Microsoft 365 admin center and click Show all.

  3.  Click Exchange in the Admin centers.

  4. Select recipients from the Exchange admin center menu.

  5. Double click on the Exchange Online mailbox that needs to be configured. The Edit User Mailbox dialog box opens.

  6. Select mailbox features.

  7. Scroll down the features and click View details of the Message Size Restrictions

  8. Increase the maximum message size in the appropriate fields and click Save. Note that it takes around 10 minutes for the changes to be applied.

  9. Open your NAKIVO Backup & Replication and run the recovery job again.