Mail Standards


The cost of mailing varies with each classification. A "flat" is a mail piece that is larger than 6 1/8" x 11 1/2". The flap should be on the right side of the envelope when looking at the address. The one exception would be when the flap is at the top. A "letter" is a mail piece that is less than 6 1/8" x 11 1/2", but larger than 3 1/2" x 5", and the flap should be at the top when looking at the address. A "post card" is a piece of mail that must be larger than 3 1/2", but smaller than 4 1/4" x 6" in size. The address on the face of the envelope should be parallel with the longest side of the envelope and should conform to the USPS specifications. The template in the additional resource section of this manual is for your reference.


First Class, Standard A, and International letter class mail weighing one once or less is non-standard if it exceeds any of the following size limits: 

  • 11 1/2" in length, or 
  • 6 1/8" in height, or
  • 1/4" in thickness, or
  • Its aspect ratio (length divided by height) does not fall between 1 to 1.3 and 1 to 2.5 inclusive

There is an additional charge of .11 cents on each piece of mail that is found to be NON-STANDARD. In addition, pieces which are less than: 

  • 3 1/2" in height, or 5" in length, or
  • .007" in thickness (thickness of a postcard) are considered
  • non-mailable in the USPS and subject to return.


Non-mailable items include: 

  • paper clips
  • metal pieces
  • pens
  • glass chips
  • pins
  • sand

Please do not enclose these items in envelopes as they will not only jam and damage the University mailing equipment they may also cause serious injury to the Mail Center and U.S. Postal employees. If sharp items such as pins, pens, and glass are mailed in a first class sized envelope they will be returned. Please use an alternative mailing envelope to mail the above mentioned items. If you are mailing a piece in any size envelope that is bound by a spiral side, the spiral side must be on the bottom of the envelope.


Intercampus mail consists of mail that is delivered to another campus location. This mail can be identified quickly by using the red and white plastic inter-campus envelopes. In addition, the white letter sized inter-campus envelopes are acceptable ways to use the inter-campus mail system. Preciseness is to be exercised when using an inter-campus envelope taking care that all previous markings have been masked out completely to ensure proper delivery. Both types of envelopes are available at the Mail Center.

Please help the Mail Center provide proper delivery of internal mail by using the required markings of a full name or department and the four-digit mail code. The mail code will help the Mail Center employee forward the mail piece to the proper building and department. The person's name will let the department office manager get the piece to that specific person. Please include the last name, as there is a good chance that there are people with the same first name in that department.

For a listing of mail codes consult the mail code directory provided, or call the Mail Center. All campus mail must have the proper mail code for quick delivery. When consulting the campus directory, please be careful not to necessarily use the department name, as mail is delivered to locations. (i.e. School of Business 3500 Business Professor whose office is in ADEP 2200) Notice the difference in numbers and locations.

* Note: Do not use inter-campus mail to promote personal business. The university's ability to use an inter-campus mail system is regulated by the USPS Private Express Statutes and Letters of the Carrier rules and regulations. No personal business and outside business should or will be handled via inter-campus mail.

Postage Paid:

Postage paid mail has been pre-paid by the sender. If a piece of mail bears postage paid postage, the Mail Center will run the mail piece through the system without any restrictions.