You're sending a letter envelope (under 3.5 oz) or large envelope (under 13 oz) that's flat and bends easily. Low rates for packages with expected delivery in 2-5 business days 4 (also the primary option for HAZMAT items that can't travel by air). You're sending important items that need to arrive in 1-3 business days. 1 You need date-certain delivery with a money-back guarantee. You're sending something urgent that must arrive next-day or 2-day. Go to the Post Office to ship heavier items like books and educational material. Mail, like postcards, letters in small envelopes (up to 3.5 oz), and large envelopes (up to 13 oz).

Review USPS Publication 52, Hazardous, Restricted, & Perishable MailĬompare All USPS Domestic Mail & Shipping Servicesįast air delivery for your most important mail and packages (with some Flat Rate options). See More Details: Domestic Shipping Prohibitions, Restrictions, & HAZMAT If you have any questions about what you may ship through USPS, review the restricted and prohibited items list. If you don’t follow the rules, you might face fines, or even criminal penalties. You have to follow all laws and USPS regulations. Some items have special packaging requirements, or can only be sent via ground transport, like perfumes containing alcohol.Perishable items (like plants or food) are generally OK to send as long as they are properly packaged and won’t spoil or leak.Lithium batteries (like the ones that come installed inside small electronics, like laptop computers or cell phones) are usually OK to send if the items are new (or a manufacturer-certified repair) if the items are used, they can only be sent via ground transport (can’t go on planes).Other items are restricted: You have to follow the rules, stick to any limits, and properly package and label your items.

Some items are prohibited (completely forbidden): You can’t send them through USPS, so you’ll have to choose another carrier.

Usps shipping box sizes flat rate