mmm! "Po box" should have been recognised and rejected.
I was hoping you would have copied the address from either or both of the Orders or Customers tables (as originally input) for comparison, as text could be changed for the order confirmation email.
While you seem to know what you are doing (utf8_general_ci => case insensitive), and I presume you have done a search and found an entry for "Po box" in the php files for this mod, I am somewhat at a loss to explain or help resolve this issue.
Best Regards
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