FAQ How do I enable Address Check to recognize non-standard suffixes abbreviations? Non-standard suffix abbreviations (i.e. Boul for Boulevard, Pk for Parkway, Av for Avenue, etc) can cause addresses not to code in Address Check. To enable Address Check to recognize non-standard suffixes you need to edit the MP4SFX.DEF file of street suffixes. This file is located in the MAILERS+4 directory. The USPS standard suffix abbreviation is on the left and the non-standard abbreviation is the right of the equal sign. Be sure to use a text editor like NotePad and not a word processor program like Microsoft Word.