If your mail hasn't arrived after 7 business days, the post office has a new solution for you to report it. Even if you didn't pay for tracking, you can report and search for missing mail or packages.
To use the service, go to https://www.usps.com/help/missing-mail.htm. You have to have an online account with USPS for it to work. Once you've logged in, the website will ask you for the mailing date, how it was mailed (such as first class), where you want the mail returned to if found, who to contact about the mail, and the contents of the mail.
As a billing agency, especially when dealing with delinquent accounts, we hear many comments such as, "I never got a bill." My office has made mistakes with mail-outs, and sometimes it's the property owner who is mistaken, but we also hear several credible complaints each billing cycle that a bill or payment was literally lost in the mail.
We also interact with many Decatur residents, dozens of whom have complained for years to us about postal delivery service in Decatur. Since the post office is a federal agency which is totally separate from city government, all we have typically been able to do is to refer those residents to the post office or to the postmaster. It is nice to know that this additional tool is available.