Server has lost 40 important messages sent to me?

Question

June to now sender's server confirmed delivery of 40 messages, various dates, which did not reach me

Answer 1

It is usual practice that mail servers has scheduled back-up data. You might want to try it. There are several causes why mail servers (I am assuming) will loose your 40 messages but that rarely happens. Try to trace the sequence of events in the logs in case the admin has it. If you have a timeframe of the messages that will help you track events. Good luck. Hope I help a little.