If your recipient signs a document and returns it to you outside Adobe Sign, you can upload that document back into Adobe Sign and keep your records tidy.
Success! Now when you look at that document under the Manage page, you see it in the Signed category. The document you uploaded is in place.
If the document is taken outside the Adobe Sign system, then all of the Adobe Sign fields are removed from the document from that point forward. (So if there were any signers still waiting to sign this document, they only have an auto-generated Signature Block field to enter their Signature and email address.)