Hi HN!
I am developing calculate@email-cost.com a chatbot whose goal is to reduce the overall emails in corporate environments --emails are not kept by the system. For the moment it only replies with the cost of your mail, taking into consideration the reading and interruption time. This is a "skateboard MVP" so feel free to play with it and comment below.
As a side note, the most expensive mail I found in my mailbox is 125.40 USD, does someone have more than that? ; )