Use standard two-letter state abbreviations. When using window envelopes, make sue the complete address is always visible, even when the insert moves. This type of addressing is not recommended. If you need to use a dual address, keep in mind the mailpiece will be delivered to the delivery point on the line above the city, state and ZIP Code. Using the correct address format will help get you letter to its destination.
Many firms have both a street address and a post office box.
If you desire, you may use both in an address. However, the mail will always be delivered to the address immediately above the city, state, and ZIP Code line. For cards larger than regulation size, 1st Class letter rates will be charged. Northeast NE Room RM Southeast SE Department DEPT Northwest NW Southwest SW UWSP Homepage.