ErrorMimeContentConversionFailed: The item we attempted to migrate is corrupt and was rejected by the Exchange server during migration because its MIME content could not be converted (from TNEF format to RFC 2822 format).
This error message indicates the item was skipped and not migrated.
In most cases, you will find that the item is non-readable from the Source mailbox. If necessary, consider manually forwarding affected items to the Destination. Alternatively, consider exporting and importing affected items using Outlook, as it may be able to correct invalid MIME content. Please note that MigrationWiz tries to repair and normalize invalid MIME content, but this does not always succeed.
Note that while we notify you of items having invalid MIME content and whose migration failed, this is not the case for most email clients. For example, Microsoft Outlook and OWA do not show items with a corrupt MIME content, so you would not know that they exist.