Certified mail is an add-on service offered by USPS for First Class mail that provides proof of mailing to the sender. With electronic USPS tracking, the sender is notified when the mailing was delivered or that a delivery attempt was made.
You send letters as Certified mail through the Lob API by passing the value “certified” in the “extra_service” parameter of the create letter request.
Please note that the Certified mail add-on is only available for First Class mail sent domestically within the US. To see the incremental cost of sending Certified mail through Lob, please refer to our pricing page.
Please also note that Lob’s Certified mail feature does not support Electronic Signature Return today.