I really like that gmail keeps related email messages in one "thread" for easy access. But sometimes an email message gets left out. (I suspect the senders email client is misbehaving.)
Is there a way to tell Gmail that I want this email message to belong to an ongoing conversation?
Best Answer
No, there isn't. You can mute a thread, but you can't cleanly merge them.
One thing you can do: forward an orphaned email to yourself as a response to the thread you want it to be a part of, then delete the original. That won't force your sender to keep things together, nor is it particularly automated, but for reading/archiving purposes it may fit your needs.