It's a quick 3-step process to sign up for it. Informed Delivery takes pictures of the letters as they go through the automated sorting machines. Those pictures are then sent to your phone or computer. We’ve told you about this free service before, but now that you’re waiting for a second stimulus check, you may actually sign up! The service is available to many residential and personal P.O. box addresses but not businesses. It also won't work for some multi-unit buildings where the postal service hasn't yet identified each unit. Activation time for the feature may vary, but typically you will begin to receive notifications within three business days. You do need to verify your identity. If you have problems with that the USPS gives this answer in their FAQ: