what can i put in a priority mail flat rate express envelope

Is Priority Mail Express 1 day guaranteed?

And this service remains the only way to have something delivered on a holiday or even delivered overnight to a PO Box. Priority Mail Express, meanwhile, is worth the extra cost if you are shipping anything under a strict timetable or if you require a delivery guarantee. USPS Priority Mail Express is the fastest domestic shipping service available from USPS and delivers your parcels within 1-2 business days.1 Is Priority Mail Express worth it? USPS Priority Mail is the standard domestic air service for USPS, and packages are delivered within 1-3 business days with tracking for domestic deliveries. Is there a difference between Priority Mail and Priority Mail Express? Priority Mail Express and Priority Mail envelopes are available at your Post Office or can be ordered online and delivered right to your door by visiting Larger items can be mailed using your own box, a box provided by the USPS, or Readypost® boxes available for purchase in post office lobbies.2

What can i put in a priority mail flat rate express envelope