how long will it take usps to deliver
January 6, 2012 By Certified Mail Envelopes. Plan on 3 to 5 business days unless you send it Priority Mail 2 or 3 day service. USPS Certified Mail provides the mailer a receipt or âproof of mailingâ and evidence of delivery when the letter is delivered. It does not guarantee an exact delivery time because someone must sign for each letter. Certified is primarily used for important notifications, compliance and business communications.