There are two ways to submit letters to our API:
address_placement = top_first_page: By default, letters will be submitted this way. You should leave a designated area on the top of the first page of your document for Lob to print the address information, which will show through our standard double-windowed envelope.address_placement = insert_blank_page: If you do not wish to update the first page of your document with room for the addressing information, you can submit your letters asaddress_placement = insert_blank_page. Lob will insert an extra address page in front of your document where we will print the address information to show through our standard double-windowed envelope. See our pricing for extra costs incurred due to the additional page.