U. S. Postal Service Mail

This is an  overview of information about the U.S. Postal Service mail. For information about specific mailings, consult the U.S. Postal Service online guide at www.usps.com or contact Mail Services @ x86783). 

Addressing for Success

Mail with the correct address and zip code saves time and money. Improperly addressed U.S. Mail is diverted for manual handling which is much slower and could be more costly.

The following is an outline of a well-addressed envelope that will ensure proper delivery. 

  • Capitalize each letter in the address area and eliminate all punctuation. Use the common address abbreviations and two-letter state codes.
  • Single space the address block. Put one or two spaces between the character groups, and at least two (but not more than five) spaces between the two-letter state code and the zip code.
  • City, state abbreviations and zip code must be the last line of the address. Never include an "attention" line or other entries after the zip code.
  • Foreign Addresses - Foreign mailings should have the country name, printed in capital letters, as the only information on the bottom line. The postal delivery zone, if any, should also be included. Following is an outline of a well-addressed envelope that will ensure proper delivery. 



  • When using window envelopes, the address (and postal barcode if used) must be the only thing visible. Make sure the paper fits the envelope to prevent the address from shifting out of the window area. Try to keep ¼" clearance between the address and the window edge. Normal window placement is ½" from the bottom and 7/8" from the left. Window size is 1 1/8" x 4 1/2".
  • When addressing envelopes larger than regular letter-size envelopes (postal nomenclature: "flats", taller than 6 1/8"), always place the address lengthwise in the center of the envelope. It is always better to type or print the address on the envelope instead of using labels, as they have a tendency to peel or tear off. Never attach or tape a letter envelope on the outside of a flat or package.

Sorting out the Mail Sorting Process 

For a better understanding of how your outgoing mail is sorted by the U.S. Postal Service, let's take a step-by-step look at the sorting process:

How the Optical Character Reader (OCR) Works:

  1. All mail passes by a computer scanner, reading the delivery address.
  2. The OCR's printer then sprays on a bar code, representing the Zip-4 code for that delivery address.
  3. Next the mail piece moves on to the OCR's sorting delivery channels.
  4. The bar coded mail piece is then fed to bar code sorters, separating mail right down to the sub-station and the letter carrier.

NOTE: If your mail piece is too large or too small, it cannot be processed by the Optical Character Reader (OCR) or the Bar Code Sorter (BCS). As a result, your mail may be subject to a surcharge.

U.S. Postal Service Size Standards

Post Cards:

Maximum Size: 6" x 4¼"
Minimum Size: 5" x 3½"
Minimum Thickness: .007


Maximum Size: 11½" x 6 1/8"
Minimum Size: 5" x 3½"
Maximum Thickness: ¼"
Minimum Thickness: .007"

Flats (larger than letter size):

Maximum Size: 12" x 15"
Maximum Thickness: 3/4"

All postcards, letters and flats not standard in size, will be charged a surcharge of 10¢ each, in addition to normal postage charges.

Priority and Parcel Post:

Maximum Size: 108" in length and girth combined
Maximum Weight: 70 lbs.