"This is a test - I've never used this feature; I always simply use the 'reply'
button - I did think you were doing something else. Are you simply in the
habit of using this feature, or do you actually belong to some mail-lists that
require that capability? I belong to about 20 mail lists currently and have
belonged to a number of others in past times, and I have never had need of
this feature. I'm sure there are some mail-lists still active out there where
the reply-to-header is not converted to force replies to the list when
messages come in, but, I've never belonged to one, and don't know of any."

Since this is a mailing-list, I use reply to mailing list. It also happens when I simply use reply to. The problem does *not* occur when I originate an email, however (no replying).

As a test, I simply clicked reply in order to answer this post. Amazingly, the To: field is correct. In the past, I have seen that sometimes *To* causes the mail to be sent to both the list and to the originator of the post (which leads to a lot of attempts at unnecessarily taking conversations off-list and private). This has happened to me a few times because I did not pay attention to the To field when replying.

So, here goes, sending a response with just Reply, not Reply to Mailing-List.