VERIFIED SOLUTION i

Does MailStream Plus validate the correctness of the ZIP Code, the ZIP+4, the 2-byte Delivery Point Code, or the Carrier Route code?

Product affected: MailStream Plus™, all versions, all platforms.
 
MailStream Plus™ (MSP) does *not* validate the correctness of the ZIP Code, the ZIP+4, the 2-byte Delivery Point Code (DPC), nor the Carrier Route (CRRT) code. 

MSP does not have the database to validate that those values are correct for an input address.  
FYI- the Street Address, City and State fields are not even mapped in the MSP parameters.   So it does not even know where those fields are in the input records, or even *if* they are in the input records.

All MSP does is make sure- 
1) 
That for the ZIP Code, either the first 3 bytes of the ZIP Code, or the whole 5 digits, *actually exist* in the USPS database as a valid 3 or 5 digit ZIP Code. (Checking at the 3 or the 5 digit level is selected based on the ZIP IN position 28 value.  The default is to check just the first 3 digits.) 

2)
And (if used) for the ZIP+4 and DPC MSP just makes sure the fields are populated with numbers. 

3)
For the CRRT, by default MSP does not validate that it actually exists.  ZIP IN position 60 does allow the option for MSP to verify if the input CRRT actually exists in the input ZIP Code.  But again, of course, MSP cannot verify if the CRRT value is correct for the mailing address.
UPDATED:  May 14, 2019