You keep yacking about postal this and that like it means something. Like you said something meaningful and you haven't. And I know edits. This place is showing how its crooked lately.
Absentee ballots arrive at election centers to be validated and tabulated one of two ways...they are delivered by the post office (which means they must be post marked) or in a batch from drop boxes. Drop boxes are emptied at the time the polls close...long before all ballots have been counted and the voter records updated. Which means you don't know who has voted and what voters you might forge a ballot for.
You claim then that you'll get the voter data base and extract the names of inactive voters....people who have not voted in years...and forge their signatures. The only problem there is that the voter data base will show they were not mailed a ballot...so how do your forgeries get through the validation step?
You brought up the ballots that were mailed to voters but not returned to be counted.
You have yet to tell us how that would contribute to fraud. Those ballots were mailed to legitimate addresses. Since they were not returned to be counted one can only assume the voter threw it away.