I agree on this. We have some subjects that see to be often repeated in unrelated threads. While the current string should be able to stay connected, I don't necessarily want it connected to the last time that subject line was used.
That should be a less frequent occurrence in Groups.io than in Yahoo Groups. Yahoo Groups would add a message to a thread if either a) the subject line matches, or b) the header fields show a reply-to relationship.
In Groups.io the new message is connected to an existing topic only if both (a) and (b) are true. So if a member composes a new message (not a reply) with a common subject line, like "Help", his message won't get connected to any existing topic in Groups.io.
