U.S. Postal Service Mail Specifications

General Information

Font Size – Use a font that is not defined as light, bold, extended or condensed.  Do not use italic, highly ornamental or script-like styles.  Postal optical character readers can recognize type sizes between 8 and 18 points. Recommended type size is 10 to 12 points.

For detailed information on proper addressing and mail design, contact Mail Services.  They will order you a publication distributed by the USPS  entitled Designing Letter Mail.  This book includes bar code specifications and all other information you need for mail design.  It is free. Allow us two weeks to acquire the book.
Postage Surcharge – There is an additional charge on each piece of mail that is non-standard size.  There is a surcharge on flat envelopes with a metal clip on the back.  Buy self sealing flat envelopes and save money.

Oversize Mail – First class, standard and international letter class mail, weighing one ounce or less is non-standard if it exceeds any of the following size standard limits:
  • Height – 6-1/8 inches
  • Length – 11-1/2 inches
  • Thickness – 1/4 inch
  • Its length divided by height is less than 1.3 or more than 2.5
Postcard Sizes – To mail at the postcard rate, a postcard must not be more than 4-1/4 inches high or more than 6 inches long.  Postcards exceeding this size require First-Class Mail letter rate postage.

MS Word Bar Codes – We recommend you DO NOT use the MS Word feature to add a bar code to your envelope address.  The USPS requires an intelligent bar code that cannot be created by MS Word.  Thus, the bar code feature could misdirect or slow down your correspondence.
How should I send it?

Appropriate Size and Strength:

Enclosures determine the appropriate envelope to use.  The envelope should be of the proper size and strength to accommodate the mailing. 
Strength: The strength of the envelope must be adequate to protect and retain the contents.  Heavy materials may require heavyduty envelopes or boxing.

Excessively large envelopes will not keep the inserts from shifting thereby creating unevenness.  This could cause ripping and loss of contents as the envelope processes through postal equipment.  A snug fit keeps the enclosures firmly positioned in the envelope.

Inserts should be folded to fit 1/8 to ? inch below the fold of the envelope flap. The strength of the envelope should be able to withstand the weight of the contents.  Stress at the seams or sharp edges inside can cause an overstuffed envelope to burst and lose its contents.  If you cannot close the flap and seal the envelope, we can’t either.

When using a window envelope, address the mail piece so that you have 1/8 inch clearance of the address around all edges of the window.  Fold the contents so that when the envelope is tapped on each of its four sides, the address does not slide out of view.  Do not staple envelope contents into place.

To ensure efficient processing of first class mail, these recommendations should be followed:
      a. Edges should be sealed or tabbed to be efficiently handled by automated equipment.
      b. Comply with the following dimensions for automated processing by the USPS:

Letter Size Mail consists of rectangular mail that conforms to the dimension requirements in the table below.

Dimensions for letter-size mail





3 ½ inches

6  1/8 inches


5 inches

11  ½ inches


.007 inches

¼ inch

Flat-size mail consists of unwrapped, paper-wrapped, sleeve-wrapped, and enveloped matter that exceeds at least one of the maximum dimensions for letter-size mail but which does not exceed any of the maximum dimensions for flat size mail.

Dimensions for flat-size mail





6  1/8 inches

12 inches


11  ½ inches

15 inches


¼  inch

¾ inch

Post cards mailed at First-Class mail rates should meet these dimensions.

Dimensions for First-Class Mail Post Cards





3  ½ inches

4  ¼ inches


5 inches

6 inches


.007 inches

.016 inches

Envelope flaps should be in the open position to properly process through our mailing equipment. Please interleaf or “nest” envelopes with the flaps up.  Please separate sealed and unsealed envelopes. ALL flats must be sealed.  

Green Bordered Envelopes 
Use only for first class mail.

Red and Blue Bordered Envelopes
Use only for airmail to foreign countries.  Since there is no airmail class for U. S. Mail, these should be used ONLY for foreign mailings.

Plain White or Manila Envelopes 
These may be used for all other classes of mail.  Please avoid the use of Tyvek envelopes. These are extremely difficult to process through our mailing equipment.  Always include a return address AND your cost center number.
Padded Envelopes
Padded envelopes have a cushioned lining to provide a degree of safety for mailing small and moderately fragile merchandise.  These envelopes are available in Mail Services for your personal purchase.

Priority Envelopes and Boxes
Used for first class mail weighing more than 13 ounces.  There is no minimum weight limit for Priority Mail items.   Mail weighing less than 13 ounces and endorsed “Priority Mail” is charged the minimum 1 pound Priority Mail service rate. Maximum weight is 70 pounds and combined length and girth of an item may not exceed 108 inches.

To Seal or Not to Seal
Seal:  If the information is confidential whether it is campus mail or being sent off campus. 

Do Not Seal:  It is not necessary to seal standard business envelopes going off campus. Seal if the envelope is oversized, over stuffed or a flat.   (Note:  If you cannot close the envelope flap over the contents, neither can we!)

We must adjust the settings on the mailing machine to  accommodate sealed or unsealed mail.  Thus, please SEPARATE SEALED MAIL FROM UNSEALED MAIL.

Standard Address Format:
(Optional) Non-address data CUSTOMER SERVICE
(Optional) Information/Attention JOHN DOE
        Recipient DOE INSURANCE AGENCY
        Delivery Address 123 ELM STREET
        Post Office, state, zip+4 LOS ANGELES CA  90012-0001
Dual Address:
Grand Products Inc.
100 Major Street
PO Box 200
New York NY 10001-0200

If you use a dual address, mail will be delivered to the line appearing directly above the city/state/zip. You should use only the street address OR only the post office box number.  In the above example, mail will be delivered to the post office box.

Return Address for your Furman Envelopes, Address Labels, etc. 

Furman University
Mail Services (Use your department name)
3300 Poinsett Highway
Greenville SC 29613-1234 (Your budget #)

First-Class Mail Service

All First-Class Mail has two common features: expeditious handling and closure to Postal Service inspection by law.  Types of mail that must be sent as First-Class Mail are:
  • Bills and invoices
  • Cards
  • Checks
  • Greeting cards
  • Letters
  • Money orders
  • Personal notes
  • Postcards
First Class mail is awarded full service by the USPS and will be forwarded, if applicable, or returned to sender if undeliverable as addressed.

Standard Mail Service

This class includes printed material, booklets, catalogs, newsletters, photographs, keys and merchandise weighing less than 16 ounces.  This mail will not be forwarded to a new address or returned to sender if undeliverable as addressed.

Priority Mail Service

Priority Mail is First-Class Mail for items weighing more than 13 ounces up to the maximum of 70 pounds, with maximum size of 108 inches combined length and girth (the length or longest side, plus the distance around its thickest part).  It is an expedited service for customers who need prompt, but not overnight, delivery.  

Handling time is 1, 2 or 3 day delivery between major metropolitan areas, depending on destination. Service is neither guaranteed nor trackable.

Periodicals Mail Service

Periodicals service is primarily used for newspapers and magazines mailed in bulk.

Package Mail Service

This mail includes merchandise, printed matter, mailable live animals, and assorted other matter weighing 16 ounces or more and not included in First-Class Mail, Periodicals or Standard Mail Service.

Postage is computed by weight and distance the package must travel to its destination.

Media Mail and Library Mail are not zone-rated.  Postage is based on weight and mail makeup.  Travel is slow but the cost is inexpensive.

Some items that qualify as Media or Library Mail are films, microfilms, test materials, printed music, play scripts, manuscripts and books.

To avoid surcharges, packages should not weigh more than 70 pounds or measure more than 108 inches in combined length and girth.  An oversized rate is charged for packages where the combined length and girth is between 108 and 130 inches.  A single piece of Bound Printed Matter mail can weigh no more than 15 pounds.

International Mail

Most items are mailable to foreign countries.  However, there are restrictions.  What is acceptable in one country may not clear Customs in another country.  Be sure you let us know what is in the envelope or package so we can make the appropriate declaration.  Failure to do so could cause the item to be impounded by Customs until the sender pays duty fees.  Many countries now restrict package weight to not more than 4 pounds.

Don’t forget.  A Customs Declaration (PS Form 2976) must be completed for international mail that weighs less than 13 ounces and has potentially dutiable contents.  If it weighs 13 oz. or more, Customs Declaration PS Form 2976-A must be completed.  The contents of your article, even if a gift or sample, must be described correctly and completely.  Failure to do so could delay your article and cause difficulty for the addressee, or even result in seizure of the article by foreign customs authorities.  Your item may NOT contain any dangerous articles prohibited by the USPS.

Some foreign countries are postal code aware.  If you are mailing to one of these countries, you must include the postal code. 

The complete foreign delivery address must be typed or legibly written (with ink) in English – using all upper case roman letters and Arabic numerals and should appear lengthwise on only one side of the mail piece.  An address in a foreign language is permitted if the names of the city, province and country are also indicated in English.

The last line of the address must include only the complete country name (NO abbreviations) written in uppercase letters.  Foreign postal codes (numeric and/or alpha) if used should be placed on the line immediately above the country name.  Some countries prefer that the postal code follow the name, while others prefer that it precede the city or town name.  The following shows the order of information for the destination address:


Exception to Canada:  There must be TWO spaces between the province abbreviation and the postal code, as shown below between “ON” and “K1A OB1”


Return address for foreign mail:

Many foreign postal administrations now require complete sender information (including zip code and country of origin) in roman letters and Arabic numerals.  Pieces that do not contain a complete return address could be returned or discarded by the foreign postal administration.  The return address should appear in the upper left corner of the address side of the mail piece.  Only one return address should be used, and it must be located so that it does not affect either the clarity of the destination address or the application of service labels and postmarks.

Please bundle international mail separately from campus and domestic mail.  Secure it with a rubber band. This will inform us that this mail requires special attention. Flats being mailed to a foreign country should also be flagged to our attention.

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