On Sat, May 23, 2020 at 05:05 PM, Malcolm Austen wrote:
Emails are (or should be) threaded on the basis of the threading headers,I disagree. If you change the subjectline, it's your intention to create a new thread.
Also, I don't want to copy one of the worst parts of googlegroups:
if you send a reply to a digest about subject A, and then send a reply to the same digest about subject B, the second message is threaded as subject A, and sent with the subjectline A ..