Unfortunately not!
I expressly removed my REPLY-TO address1 (= address 1 is the member of the list) and double-checked three times. I also scrutinued the headers of my test mails, which were accepted where they should not.
At the moment, I am scared. I discovered the issue when sending to real mail, where I set up someone as a moderator, where I am neither with address1 nor address2 member, that list had "moderate mails from non-members" set, but at this list I was added by having my addresses in our @whitelist@mydomain.com.
Because I thought, that being in the whitelist could cause my mail passed directly to the recipients, I started tests.
Perhaps you can test this at your site?
I need to say, that address1 and address2 (and a third address3) are addresses of myself as the admin-owner of the whole mailman3+mailmanweb stuff. Can this explain? But hopefully not.