I'm not sure the seller would have a notice - base

I'm not sure the seller would have a notice - based on the pdf article, it's an automated system that attaches the due bill to the shares as they are traded around. I assume when the dividend shares are released by GNBT, they go to the DTC and the DTC is responsible for distributing them to the proper owners, without them ever going to the shareholder that sold between the record and ex-div dates.