2020 email correspondence between professor Władysław Narkiewicz, a very patient mathematician, and Dr. Kumar Eswaran, who claimed to have proven the Riemann conjecture.

It ends with this beautiful conclusion:

Although our views on your result are somewhat different I want you to know that I enjoyed our discussion which showed that the notion of a proof may have different interpretations.

A summary of the correspondence can be found at skeptics.stackexchange.com: Have mathematicians concluded that an Indian mathematical physicist has solved the Riemann Hypothesis?