The Postal Service has several service enhancements, called extra services, available for use with First-Class Mail service. Extra services can be purchased for an additional fee. The extra service that is generally of most interest to election officials is Certified Mail service. The service provides the sender with a mailing receipt and, upon request, electronic verification that the Postal Service delivered or attempted to deliver the mailpiece. For further information, see DMM 503.3.0 at https://pe.usps.gov/text/dmm300/503.
