Are proxies allowed in mail-in votes?

The purpose of a proxy is to allow someone to vote without being present. In presidential and municipal elections, proxies are illegal, and the problem of an absent voter is handled with an absentee ballot.

Most railway museums and many other membership organizations, vote by mail. Robert's Rules of Order has a procedure for that (RONR p. 409, line 19) People are allowed to bring their ballots to the meeting, but in practice, few people do.

Proxies have no purpose whatsoever in a mail-in election. After all, everyone can vote by mail, and at SMRS they have over 30 days to do so. That amply serves the needs of absentees. Therefore proxies are totally unnecessary and redundant.

In any case, people cannot vote during the meeting. The ballot box closes at the start of the meeting. That's because, as Robert's Rules discusses (RONR p. 409, line 4 etc.), you can't have some people vote prior to discussion while others vote after discussion. They'd be voting on different things.

Now read what Robert's Rules has to say about any form of absentee voting:

It is a fundamenal principle of parliamentary law that the right to vote is limited to the members of an organization who are actually present at the time the vote is taken in a legal meeting, though it should be noted that a member need not be present when the question is put. Exceptions to this rule must be expressly stated in the bylaws. Such possible exceptions include: a) voting by postal or electronic mail, or fax, and b) proxy voting. (RONR p. 408-409).

Sounds like if either mail or proxy voting is done, it must be expressly stated in the bylaws. Mail is specified - proxies are not!

Can both systems be used at once? Plainly, that would be bizarre and redundant. Let's look at Robert's Rules, RONR p. 571, line 24: "If the bylaws authorize certain things specifically, other things of the same class are thereby prohibited." Now wind back to page 408 above, which puts "mail" and "proxies" in the same class - both are methods for absentee voting. Note also Robert's emphatic criticism of proxies on page 414 line 15 (near the bottom of the last blog entry) Which do you think is more likely:
1. Robert's Rules endorsing an awkward scheme allowing both mail-in and proxies? Or
2. Robert's Rules disallowing proxies as redundant to mail voting?

What do you think?