Classes of U.S. Mail

Express Mail

Express Mail is the premium delivery service offered by the Postal Service. It is the quickest way to mail an article to its destination, providing delivery overnight, or second day. It is the only class of mail for which a delivery time for domestic shipments is guaranteed. Any mailable article that conforms to size (length plus girth

Express Mail International Service is also available for most foreign countries. Please note that Express Mail does not deliver to all ZIP Code areas; please call us to determine the availability of this service. Express Mail may be received at the post office between 9:00 a.m. and 4:15 p.m. Express Mail envelopes and boxes are available at no extra charge.

Merchandise sent via Express Mail is insured against loss or damage at no additional cost to the sender, with a coverage maximum of $100; additional insurance may be purchased with a coverage maximum of $5000. Document reconstruction insurance is also provided for non-negotiable documents with a maximum liability of $100.

Express mail may be tracked by calling 1-800-222-1811 or at the website A full postage refund is made for all domestic shipments delivered later than the guaranteed commitment.

Priority Mail

Priority Mail is actually an extension of First Class Mail. Anything sent as First Class Mail which weighs over 13 ounces is considered Priority Mail. Pieces weighing less than 13 ounces may be sent Priority Mail at the sender's request. Priority Mail delivers items weighing up to 70 pounds in two days between major markets, and provides three day service elsewhere. Please note that the Postal Service does not guarantee two-day delivery of Priority Mail. Priority Mail may be used for sending contracts, documents, forms or any important items that require prompt, but not overnight delivery.

"Flat-rate" Priority envelopes are available at no charge. If an items fits into this special envelope, it may be sent Priority Mail, regardless of the weight. Priority envelopes, boxes and labels are available at the post office. Special services that are available for First Class Mail may also be purchased for Priority Mail.

First Class Mail

All First Class Mail has two common features. It is provided expeditious handling and is closed to postal inspection. First Class Mail must be used for:

  • typewritten letters
  • greeting cards
  • postal cards
  • checks
  • bills and statement of account
  • money orders
  • personal correspondence

First Class Mail weighs 13 ounces or less. Letters cannot exceed 11 1/2" in length, 6 1/8" in height, 1/4" in thickness, or 3.5 ounces in weight. If one dimension or weight exceeds any one of the above, the piece becomes a Large Envelope. Maximum dimensions for a Large Envelope are 15" in length, 12" in height, and 3/4" in thickness. If one dimension or weight exceeds any one of the above, the piece becomes a Package. The maximum weight for a Package is 70 lbs. and length plus girth combined cannot exceed 108". Postcards cannot exceed 4 1/4 inches by 6 inches to qualify for the postcard rate. Special services that may be purchased with First Class Mail include certified, registered, return receipt, and restricted delivery. Insurance is not available for ordinary First Class Mail. Letters that only contain correspondence cannot be insured. Insurance is for material of intrinsic value only. Correspondence may be sent by certified mail.

Standard Mail (Parcel Post)

Parcel Post is used for parcels weighing one pound or more. Parcels may weigh up to 70 pounds and measure to up 108 inches in length and girth combined. The delivery standard for parcels is 2-9 days, depending on the distance to the destination. Standard rates are determined by weight of the parcel and the distance to the destination ZIP Code. Special services that may be purchased include insurance and return receipt service. 

Media Mail

Media Mail rates are available for books, films, audio and video recordings, printed music, manuscripts and printed educational reference charts. Postage for articles mailed as Media Mail is determined by weight. Special Services that may be purchased with Medial Mail include insurance, return receipt service, and delivery confirmation. 

Special Services

Certified Mail

Certified mail is designed to provide individuals and business firms with proof of delivery. The service provides the sender with a mailing receipt and a record of delivery is maintained at the recipient's post office. The addressee will sign for the item when it is delivered. No record is kept at the post office from which certified mail is sent. Certified mail is handled as ordinary mail during transit. Certified mail is for domestic use only and is available only for First Class and Priority Mail. Special Services that may be purchased in addition to certified mail include return receipt and restricted delivery.

Return Receipt

Return receipt is the sender's proof of delivery and identifies the article by number. The receipt will be returned to the customer after the item has been delivered and will show who signed for it, the date of delivery and the addressee's address (if different). For an additional fee, the customer may request Restricted Delivery service by which delivery is made only to the addressee or to an individual authorized in writing to receive mail of the addressee. Return receipt may be used with Express Mail, Certified Mail, Registered Mail and Insured Mail.

Delivery Confirmation

Delivery confirmation is a low-cost, easy-to-use service that lets customers know when their mail piece has been delivered. The customer will receive the time, date and ZIP code of delivery. Delivery confirmation may be purchased for First Class Parcels, Priority Mail, Media Mail and Standard Mail (parcels only). This service may be combined with insurance and registry. Delivery confirmation includes a mailing receipt with the tracking number. The customer can obtain delivery information by calling 1-800-222-1811 or by visiting the USPS website at

Insured Mail

Insured mail is designed to provide indemnity for loss, rifling or damage. The maximum indemnity payable is $5,000. This service provides the sender with a mailing receipt and a record of delivery is maintained at the addressee's post office. No record is kept at the post office from which insured mail is sent. Packages may not be insured for more than their value. No payments are made for sentimental losses or for any expenses incurred as a result of the loss. Return receipt, restricted delivery, and delivery confirmation may also be purchased with insured mail. Insured mail must bear the complete names and addresses of the sender and the addressee, and must be adequately packaged to withstand normal handling. Packages insured for $50.00 or less do not require the recipient's signature; item's insured for amounts over $50.00 require a signature. 

Registered Mail

Registered mail is designed to provide security for valuable and important mail, plus evidence of mailing and delivery and indemnity in case of loss or damage. Registered articles are placed under tight security from the point of mailing to the point of delivery. It is the most secure service the Postal Service offers. The maximum insurance liability is $25,000. Fees are based on the value of the article being mailed. Registered mail may be used with First Class and Priority Mail.

Registered mail must be sealed with paper tape.


If your insured, registered, or Express Mail article has been lost or damaged, you can file a claim for indemnity. We will be glad to assist you in completing a claim form. You will need to provide the original mailing receipt and evidence of value. Certain waiting periods and time limits apply.