Received from David M at 7/10/2018 09:05 AM UTC:
It may be useful for those with good intentions, but it's a bad thing because it overrides the settings the Owner/Moderator thought he was making when deciding whether responses should be directed to the group or to the author being replied to. And - as one example - imagine engaging (foolishly) in a "candid" discussion about your boss and then have someone set the boss as the "Reply-to:" address.
You too seem to have overlooked that this is an announcement group. Only the admin can send messages to it, and any replies go only to the admin. If the admin chooses to add a Reply-To: for an individual message, this is a good thing, because it saves him/her having to forward all the incoming replies to someone else.
I overlooked nothing.
If subscribers to any group - announcement or discussion or whatever - expect replies to go only to the admin... or to the group... or to the poster being replied to... then I think it's improper to allow the admin or a subscriber to direct them elsewhere via embedded "Reply-to:" headers. Granted any party receiving email from the group is capable of redirecting it manually, but I think Groups.io shouldn't become a party to it.
Anyone is currently capable of forwarding messages they receive to anyone they want to, and I believe that's how Groups.io should require them to handle the sort of message redirection you're asking for. That also (usually) provides a record of WHO caused the redirect. That's also a good thing.
Expanding on my concern... when I left Y!, I left Y! behind. Groups.io is what it is... and what it is is better by far than Y! in more areas than reliability. Groups.io can be improved - the search facility currently being discussed is one example - but I'd rather not see some of the bad aspects of Y! brought to Groups.io just because some found them convenient on Y!.
Jim H