Error: FailedToMailEnablePublicFoldersException:

Hi RajajiT,

The error message "FailedToMailEnablePublicFoldersException" indicates that there are public folders that could not be mail-enabled during the migration from Exchange Server 2013 to Office 365. This can happen if the mail public folder objects in Exchange Online are out of sync with the Exchange deployment.

To resolve this issue, you can try the following:

The best working solution to the error message "FailedToMailEnablePublicFoldersException" is to:

1. Rerun the Sync-MailPublicFolders.ps1 script on the source Exchange server. This script will update the mail-enabled public folder objects in Exchange Online Active Directory.
2. Delete the public folder mailbox in Exchange Online and create a new one. This will ensure that the public folder mailbox is properly configured.
3. Restart the public folder migration.

Here is a link to the Sync-MailPublicFolders.ps1 script: https://www.microsoft.com/en-us/download/details.aspx?id=46381

Here is a link to an article on how to migrate public folders from Exchange Server 2013 to Office 365: https://www.stellarinfo.com/blog/migrate-public-folder-to-office-365/
Batch migrate Exchange Server public folders to Microsoft 365 or Office 365 | Microsoft Learn