We do not have vote by mail in France since 1975 and I do not have a clear understanding of how it works in the US - but from what I read the time validity of such a vote is decided upon the post office stamp on the letter.
I also hear that President Trump asks for some counting to be stopped (the idea being probably that these will be in majority Democrat's votes).
On which legal basis is this even possible? Such voting is allowed by law so except changing it on the fly (by setting a limit other than, I believe, the Electoral College vote early December) is this a power the president would have?