Trump is going to suppress his own voters, because he is too fukking stupid to realize so many times, is that the normal option of people going to polls is going to be reduced. If your in a big city, with tons of Democrats, there will be a reduced amount but some will be open.
If you in a rural area, with maybe 5-7 polling locations, there might be only one location or none because you need polling workers along with the mechanism to count votes. For a ton of rurals, they only have one post office, and it's not a post office that works as a hub; its the end point.
So if your fukking with the mail, you will be hurting more Republicans than what you think you wouldn't be doing. Yeah your getting Democrats, but your still hurting your own base as well.