Hi @Anonymous,
I want to know what you want to save in the list and what form to save.
Currently, you could save the attachments of the email as attachments to the list item, or export the entire email as an attachment to the item.
I am afraid I don't fully understand your needs.
Could you provide more explanation?
In addition to how to save as an attachment to list item mentioned above, you could refer to this method:


In the attachment of the item, the attachment of the mail and the exported mail of the entire mail can be viewed:

Best Regards,
Barry