Postal Addressing Standards > 3 Business Addressing Standards > 35 Address Data Element Compression Guidelines > 354 Special Characters
“Remove special characters, multiple blanks, and punctuation in order as listed below.”
Double spaces/blanks change to single space or blank, except between state abbreviations and ZIP Codes or ZIP+4 Codes.
Asterisks, except in the Optional Endorsement Line
Hyphens, except in the ZIP+4 Code and in the primary number used in the Delivery Address Line. Spaces before and after the hyphen or slashes (/) should be removed from the address or firm line.