Count list items with .msg file extension

Hi,

I would just like to ask if theres a way in filter condition in Content type mapping > filter where we can check if an item with '.msg'  file extension exists in a document library?  Or if theres documents within the library? We just wanted to apply this filter condition:

Migrate content from source to target and have a condition like this:

 - if no existing files found in the document library, force the target to have content type Email and Document. 

 - if there is a .msg file found in document library, mapped to target's content type Email | if not .msg file, then mapped to target's Document content type

- if no .msg file found and only documents found, force the target to have content type Email and Document. 

Is this possible to happen using content type mapping > filter in Metalogix? Please advise

- Regards,

Bryan