What does MailStream Plus check to see if a Letter piece is Automation compatible or not?

When the P ATTR aspect ratio for length and height exceeds the USPS automation rules, MailStream Plus (MSP) is not giving any warning in the MSP letter job or change these pieces to the nonautomation rate.
Length  is 10.5
Height is 4.13

MSP only validates the weight and thickness against the a
utomation compatibility rules
Because the P ATTR parameter allows the length and height fields to be blank if the volume is entered, MSP  doesn't check the value of the length or the height.
Once the job has the Y in position 66 of the P ATTR, MSP thinks the piece is automation compatible. (unless the weight and/or thickness exceed the automation compatibility rules)

DMM Standards for Machinable Letters says:
Within an aspect ratio (length divided by height) of 1.3 to 2.5, inclusive

This aspect ratio is 2.54 which is above the 2.5 allowed. Following this rule, this is not an automation compatible piece and the Y should be an N in position 66 of the P ATTR.

UPDATED:  April 28, 2017