Can you please help me understand the purpose of Delivery Mode = "Description" while creating an External Account? Is there a way that I just populate nmsBroadlogRcp table without actually sending any emails or generating any files?
If I understand correctly your request, then yes, this mode is designed for non-executable deliveries, meaning that any delivery with this type of routing won't be analyzed/prepared nor sent.
For logs, I assume that you could upload logs from an external system and match them with these "Description" deliveries, but I'm unsure of what importing logs involve technically, since many things are linked when it comes to logs.
Hope this helps, let me know the result of your attempts.