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US Postal Service Information

Central Michigan University Mailroom has organized important U.S. Postal Service (USPS) information for your reference.

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Addressing for automation

To insure the best possible service, speed and readability by an OCR (Optical Character Reader), the United States Postal Service (USPS) recommends that you use these automation requirements:


Mail pieces smaller than the dimensions below are not mailable. Letter mail larger than the dimensions is mailable but must bypass the OCR and be processed through slower and less efficient manual methods.

Dimensions (inches)MinimumMaximum
Height3 ½6 â…›
Length511 ½

* Card stock should not exceed .0095"

Address location

The OCR looks for the address within a rectangular space on each mail piece, called the OCR read area. No portion of the return address should appear in the OCR read area.

Address lines

Keep address lines in the same order as shown below. Make sure the address is as complete as possible including all apartment (APT) or suite (STE) numbers and proper delivery designations such as RD, ST, NW, S, etc.

Address characters

Capitalize everything, using plain block letters or a Sans Serif typeface such as Helvetica (use 10- or 12-point type). Omit all punctuation, except the hyphen in the ZIP+4 code. Use abbreviations whenever possible.


The OCR must see a clear vertical space between each character and each word or it won't know where one ends and the next begins. It also needs a clear horizontal space between each line of the address. Clear spaces between words should be at least equal to the width of one full-size character. 

Barcode clear area

The barcode clear area must remain free of all printing, markings, or colored borders and allow for a clean display of the barcode.

Non-address information

Extraneous printing such as advertising copy or university logos should be positioned above the OCR read area. The space below and on either side of the OCR read area should be clear of all printing and markings not actually part of the address.

Foreign addresses

Foreign mailings should have the full country name (not abbreviated), printed in capital letters, as the only information on the bottom line. The postal zone, if any, should be included with the city. 

For Example:

Windowed envelopes

The entire address must always be visible through the window. If part of the address is hidden, the OCR will reject the envelope and send it off for manual processing.

Print quality and color

The OCR performs best with black ink on a white background. Keep the ink as dark as possible and the background as light as possible.

Business reply mail

When departments send out pre-stamped envelopes, the department pays $.68 for each envelope and may not get the survey back, therefore, wasting postage money. The current rate is $.813 each for a first-class one-ounce business reply envelope, and a department only pays for the ones that are returned.

Note: If you expect a response rate of less than 80% it would be more cost-effective to use a business reply envelope rather than placing a stamp on the return envelope.

Classes of mail

Priority Mail Express

Previously Express Mail, this class includes letters, documents and merchandise that require a quick delivery. Express mail is the only overnight service delivered 365 days a year. Delivery should be by noon or 3:00 p.m. the next day. Some destinations are a guaranteed 2-day delivery. Price includes proof of delivery signature record (if requested at time of purchase), and tracking information with USPS Tracking and up to $100 in insurance coverage.

Priority Mail

This service offers fast delivery in 1, 2, or 3 business days based on where your package started and where it’s being sent. Limited insurance coverage against loss or damage, and USPS Tracking included at no additional charge. 

First Class Mail

Includes all matter wholly or partly in writing or typewriting, all actual and personal correspondence, all bills and statements of account, and all matter sealed or otherwise closed against inspection. Services available for First Class Mail include: certified, registered, restricted delivery and insurance. These additional services can be requested by noting the service on a meter slip and attaching it to the appropriate piece of mail. First Class Mail is generally delivered overnight to locally designated cities and within 2 days to locally designated states. Delivery by the third day can be expected for the remaining outlying areas. 

Marketing Mail

Used primarily by retailers, catalogers, and other advertisers to promote their products and services. Churches and other charitable organizations may take advantage of attractive non-profit rates for their mailings. The minimum volume needed to take advantage of either the regular Standard Mail A rate or the non-profit rates is 200 pieces per mailing. The pieces must weigh less than 16 ounces. 

Retail Ground​

Previously "Parcel Post," this class is used for packages weighing 1 pound or more. Insurance can be purchased to cover the value of the articles mailed. Packages mailed within the continent of the United States may weigh up to 70 pounds and measure up to 130 inches in length and girth combined.

Media Mail

A cost-efficient way to mail books, sound recordings, recorded video tapes, printed music, and recorded computer-readable media (CDs, DVDs, and diskettes). Media mail cannot contain any advertising except incidental announcements of books. The maximum weight is 70 pounds. Additional services can be added.

Suspicious mail or package

This message is not to alarm you, but to help reassure you and your staff members who handle unopened mail that there are a number of safeguards, in place and to heighten awareness regarding suspicious letters or packages.

Various office locations around the country have, and continue to receive threat letters through the mail. These letters may state that you have been exposed to anthrax or other biological materials. Additionally, these envelopes or packages may contain some type of powder or granules. The following information and recommendations (collected from various sources) are being provided to help you safely and effectively handle these types of incidents.

1. Firstly, all campus personnel should maintain an enhanced awareness of receipt of suspicious letters or packages. Some common things to look for include:

  • Packages with no return address or excessive postage.
  • Misspellings of common words or restrictive markings such as "personal" or "confidential".
  • Items protruding from the envelope or package, wet areas, openings, or strange odors.
  • Unusually heavy envelope and/or the presence of small bulges of powder or granules.
  • If you are concerned about a particular envelope or package, DO NOT OPEN IT. There is no risk of a release of materials or risk of exposure to you if the envelope or package remains intact. Call 911 (if on campus which will connect you to CMU Police) and inform the emergency dispatcher that you have a suspicious envelope or package.

2. If you open an envelope or package and you find a letter that contains a threatening message or states that you have been contaminated with anthrax or some other biological substance, and no substance is found:

  • Replace the letter in the envelope and place the envelope in a plastic bag.
  • Wash your hands with soap and water.
  • Call 911, remain at your work location, and wait for emergency responders to arrive.

3. If you open an envelope or package and you observe some type of powder, REMAIN CALM:

  • Slowly and carefully place the letter back in the envelope and put the envelope in a plastic bag if possible and seal it. If a plastic bag is unavailable, place the envelope on a counter or floor and cover the envelope with an empty garbage or recycling container. Do not walk around the office to show other people, nor invite co-workers to come in and take a look.
  • Immediately wash your hands with soap and water.
  • Extensive body decontamination (i.e., removing clothing, showering) is not indicated.
  • Call 911 immediately to report the incident, and remain in place to assist emergency responders.

4. If any powder spills out of the envelope or package:

  • Do not clean it up yourself, and prevent others from contacting it.
  • Do not brush off your clothes and disperse the powder into the air.
  • Wash your hands with soap and water.
  • Call 911, inform the emergency dispatcher of the incident, and what steps you have taken.
  • Remain in place and carefully remove your clothing and place them in a plastic bag.
  • If possible, shower with soap and water and put on fresh clothing. It is not necessary nor is it recommended that you wash with bleach.

5. If there is a small explosion or release of an aerosol spray from a package:

  • Vacate the space immediately and prevent others from entering.
  • Call 911 immediately and remain on the premises to provide information to emergency responders.
  • Treat yourself and your clothing as in #4, above.

People who may have been present in the room but did not have direct contact with the letter or substance are at minimal risk for exposure. Individuals not in the room at the time when the envelope or package was opened are not at risk.

For biological agents to be effective, terrorist agents must be aerosolized into an extremely fine mist that can be inhaled. Technically, this would be difficult to accomplish. Hence, the opening of mail and handling of biologically contaminated objects (e.g., those containing anthrax) are insufficient activities to aerosolize particles, and so, the likelihood of becoming infected through inhalation is minimal. However, when handling contaminated items, the risk of developing a cutaneous (skin) infection is increased when you have sores or open wounds in areas that are exposed to such contamination. In either scenario, getting a prompt diagnoses, and the availability of effective antibiotic treatments can lead to recovery from a potential infection. Anthrax is not contagious and cannot be transferred from person to person.