Certified Mail provides the mailer with optional proof of mailing and a record of delivery at the delivering post office. The record of delivery is retained for two years by the U.S. Postal Service (USPS). Certified Mail travels en route with all other First Class Mail and receives no identity until it reaches the delivery post office. In situations where proof of delivery is the real concern and the item being mailed has no cash or intrinsic value, Certified Mail would offer a viable alternative to Registered Mail.
Only mail-able matter on which the First Class or Priority rate is paid may be mailed as Certified Mail. Certified Mail along with a Return Receipt is a good way to send First Class Mail if you need proof that you sent it and proof that the recipient received it.
Contact Mail Services for more information on sending Certified Mail.