RE: Unable to migrate marketing emails between instances using configuration migration tool
Hi Tez4,
I tested the process without problems: export the data and schema file(Marketing Email) from crm123 and import them to crm456.

In both of my two environments, no customizations are added to Marketing Email entity, so dependent components shall not be required.
Please check whether you have meet these prerequisites for the export/import process:
1. Make sure no records are in a "live" state. Attempting to transfer live records will cause the Configuration Migration tool to fail.
2. Ensure that the source and destination environments are running the same version of Dynamics 365 Marketing and are using an identical database schema (at least for the data you are transferring)(For example, if a custom field was added to Marketing Email entity of source environment, while the entity of target environment keeps default settings, it may causes error.).
https://docs.microsoft.com/en-us/dynamics365/marketing/transfer-data#prerequisites-for-the-exportimport-process
If it still not works, please share error message given by configuration migration tool.
Regards,
Clofly