File Attachment Type Issue

When using the Send Email with Attachments action in a pipeline, I'm using the file_transfer_handle value for the URL field. When this action is triggered, the email is sent to the recipient with the attachment, however, the file type is lost and therefore the recipient has to explicitly specify the file type when saving the document which is not ideal. What do I need to do to preserve the file type so that if the attachment in the record is of PDF type and the pipeline sends an email with that attachment, the recipient sees a PDF attachment in their email. Thanks!