How do I do a "reply to all" when replying to an e-mail?

When is a good time to stop replying to an email thread? What can be a good last reply?

• I am often lost when it comes to email threads where there have been 3-4 emails already exchanged. Should I reply when the last email from the other person says something like "great to catch-up with you. Let's stay in touch" . I also realized that I tend to procrastinate  a lot when it comes to communication simply because I don't know what the right next step is.

• Answer:

  Simple! When you lost hope from the person you're writing to(In any context) or when time interval between two messages starts becoming 2 or more days. "Somtimes solutions aren't so simple, sometimes goodbye's the only way."