Do you use the USA Regulatory Address Cleanse (URAC) transform in certified mode to do mailings with the USPS? CASS cycle N goes into effect August 1, 2011. To remain CASS compliant you will need to upgrade to Data Services 188.8.131.52 or later.
Be aware that a major change for CASS cycle N is SuiteLink processing will now be required to run in CASS certified mode. This option requires the licensing of SuiteLink directory data. Prior to upgrading be sure you have the SuiteLink directories available.
Futher details concerning the mandatory SuiteLink implementation can be found in the following blog: