I already tried my luck on StackOverflow but unfortunately without any result. I struggle with some basics and I don't know how to solve the following problem.
I have given the following data structure in Elasticsearch:
...and other stuff...
How to answer, for instance, this question: Return all email addresses which occurs more than X times. This seems very trivial but for instance how to join 'sender_email' and 'receiver_email' so that we have just one column? How to apply a 'where' clause where I can set a threshold?
How would the solution look like in Kibana and how on the console with curl?