Mail of any kind for transport by the United States Postal Service should be enclosed in an appropriate envelope or parcel and sealed. The types of enclosures that determine the mailing classification.

             NON-MAILABLE MATERIALS

The following are examples of materials which should not be mailed in envelopes:

• Pens and Pencils
   
• Paper Clips
   
• Glass Chips
   
• Staples
   
• Metal Pieces
   
• Sand

Such materials will not only jam or damage the mailing machines, but can also cause serious injury to Mail Services employees.

In general, any material which causes a bulge should not be mailed in an envelope.


In addition, the following are also classified as non-mailables and may be returned to sender:

Envelopes and Cards if these pieces are less than:

• 3 1/2 inches in height
   
• 5 inches in length
   
• .007 inches in thickness (thickness of a post card)

Foreign countries often have unique restrictions regarding enclosures. Check with the Mail Services Manager if in doubt.

             WINDOW ENVELOPE ENCLOSURES

Enclosures, designed so that the address appears in a window envelope, must not be stapled to prevent slippage of the address from window view. If the address enclosure does not properly fit the window, use an envelope without a window. Please do not staple mail into envelopes.