The United States Post Office does not have an official program. However, there are other ways to get such attention.
There are telephone reassurance programs. When you are signed up
for one of these, a volunteer will call each morning at a certain time. To find such a program call Information and Referral. Or call aging services at your state or county offices. There are other programs as well. Some states have Gatekeeper programs whereby mailmen, utilities repairmen, and even banks are trained to be alert for trouble. An older person might wait by the mail box each day. If the post man does not see this person for a day or two and the curtains are shut, he might check. Maybe the elder has gone away on vacation. Or the person might need help.
If you check with city, county and state Information and Referral Services, you may find valuable services to reduce the isolation of an elder.