Customers buy a block of postage, then print the stamps electronically with laser printers.
Each stamp has a two-dimensional bar code that provides a unique, scannable signature. The code includes postage amount, source and destination ZIP codes, and date and time of electronic printing. That's more information than you find on meter marks made by postage meters. Local post offices will have to install scanners that read the stamps and record information. That should speed the mail along and help keep customers honest.