How do I know if an email has been opened?

8 năm trước

16:38, 04/08/2015

I believe there is a way of knowing whether an email has been received/opened by the recipient. How do I do this on Thunderbird?

Answer 1 · 2015-08-04 16:38:38

19:21, 04/08/2015

There is no guaranteed way to know this. You can ask politely for confirmation. The recipient can choose to ignore your request.

You'll find that services like gmail quietly swallow such requests on incoming messages and don't even show them to the user.