Content Matrix does not preserve the content authorship (Created By, Modified By). Instead, it replaces it with the migration account.
For SharePoint On-Premises:
This is a SharePoint API limitation. When Content Matrix copies a user, a method such as validateUser will be called to check if it is in Active Directory and active. If not, the SharePoint API will not allow Content Matrix to add it.
For SharePoint Online:
If you are using Content Matrix 8.3.0.3 or above, you may be able to preserve authorship for disabled Active Directory users when migrating to SharePoint Online using the Azure API by selecting the "Allow copying of deleted Active Directory users" option in the Mapping Options tab.
Note: for this option to work, we need to use Import Pipeline, Either Azure public storage or Private Storage
Below are some references:
