No "mail-in" ballots should be accepted if they have no postmark on them, or if the postmark is not legible.  Unlike in-person voting, where individuals are physically present and they submit their votes within a controlled environment where the votes are secured and counted, mail-in ballots could originate anywhere and on any date.  Lack of a postmark means that there is no evidence that ballot complied with the Virginia state legal requirements for postmarking by the election day; a postmark is evidence (from a third party outside the vote-counting process) that the ballot has met the legal requirement for timely mailing.  Without a postmark to confirm compliance with the submission-date requirement, the ballot should be rejected as non-compliant.  Mail-in ballots are risky enough and for many reasons: unlike in-person voting where the vote is cast by the physically-present voter and counted within the same space; ballots mailed to voters can be intercepted in that mail-delivery process; mailed ballots can be lost by USPS in that mailing process; the ballots can be stolen from voter's mail boxes;some ballots are being sent to wrong addresses (are ballots being sent ONLY to registered voters?); some individuals have received more than one ballot; similar issues can arise during the mailing of the ballot vote; USPS mail handlers can interfere with mail delivery----there is no need to increase the risk of fraud or loss of votes by purposefully violating Virginia law and accepting ballots submitted without the proper postmark.  The postmark is the bare-minimum, but essential, requirement that these ballots need to meet!