Got many P.M's about this after my post about a seized package started to answer a few. I think this is easier long story short!
You do nothing its a Customs letter! It tells you they have seized your package. And they give you a form to dispute it if you can prove its not of Cuban origin. Which you can't because it is, so they keep it end of story. The fine letter is the OFAC letter i got one years ago. A vendors records where compromised through the payment processor.
He cooperated with the Govt and gave everyone up. Cost me $1,500!
I saved my letter from last year. Wanted to frame it but the govt is so wordy it took them six pages to make their point. I inexplicably lost a box at the beginning of October but no letter yet so I am hoping a postal employee is giving away a box of Monte #2s this Christmas to a botl in need.