开云体育

Frances,

It looks like threads don't automatically close. This must mean someone
can add to an old thread a year or two later. Correct?

Yes, but only by replying to a message in that thread.

If I don't want that, I must manually close them. Right?

In most cases closing the old thread won't be necessary, Groups.io will do what you want automatically.

Groups.io has fairly tight requirements for adding a new message to an existing thread, this is unlike Y!Groups where a matching subject could add a new message to a thread that is years old.

Closing a thread prevents new replies to the thread, but does not prevent new posts with the same subject (see below). An attempted reply to a closed thread is rejected, it does not start a new thread.

Perhaps a dumb question but I assume that subject lines from closed
threads can be reused later. For example, if the subject is Malta, can
someone else later start a new thread with the subject Malta?

Whether the old thread is closed or not, a new Post (not a Reply) with the subject "Malta" will start a new thread.

There is one exception: if the new post has the subject "Re: Malta" and is posted within a week of a message in the thread, then it is presumed to be a reply to that thread. If the thread is not closed the new message will be added to it.

For members that post by email, the distinction between a reply and a new post is, generally speaking, whether they used the "Reply" function on a message they received versus using Compose (or New Message, or whatever it is called in their email service).

The technical details are in beta@ message 5772:
/g/beta/message/5772

Shal