I can accept some kinds of absentee ballots, but those should still be able to be handled within reason, with a strong chain of custody, including signature verification and address audits. Possibly not even mailed out, but just picked up at the local BoE, with the ballot printed in accordance with the voter's original jurisdiction, handed back to that local BoE in person, and mailed out to the voter's original BoE. Absentee votes can be done reasonably, but mail-in (really: mail out voting) has no reason to exist.