Some countries do use electronic voting (using state PKI based systems) that in many sense is similar to mail-in ballots. I can recognize two problems with the

Some countries do use electronic voting (using state PKI based systems) that in many sense is similar to mail-in ballots. I can recognize two problems with these. a) vote buying, b) vote stealing. Risk for vote buying is similar for both methods but electronic voting has in my opinion higher vote stealing risk as it is easier to implement on large scale. I think both methods are suspicious and I am not in favour of them, but as usage of mail-in voting is not widespread, it does not involve too big risk. Contrary electronic voting may become very popular and problems will be magnified.