Sure this "etc, etc" is out of place as you point out. Though Joe's explanation pretty much said it, because you are asking Japanese translation, I came up with time-honored, rather stilted expressions.
These are common ending words for Japanese mail, and by itself it expresses respect to the recipient, just as "sincerely yours", "respectfully yours" and/or "best regard" do in English.

In essence the writer is expecting you read his/her feeling between the lines.