If you are writing an address, whether typed or handwritten, on an envelope to be mailed via the post office, do not use any punctuation. Use all CAPS. Center the address on the envelope and use a flush left margin. Put room, suite, and apartment numbers on the same line as the street address.
4325 W PALM BEACH RD RM 419
SAN FRANCISCO CA 94116
If you know the four-digit extension of the zip code, the post office will be even happier with you.
Also, note that you should use RD for Road and W for West. Other abbreviations: STE for Suite and APT for Apartment.
If you are writing an address in the body of a letter, use punctuation.
Example: Please send mail to Jessie Santana, 4325 W. Palm Beach Rd., San Francisco, CA 94116.
Posted on Wednesday, January 17, 2007, at 6:42 pm