David Sherman wrote:

This morning as I was seating to check the weather, I noticed that a
piece of mail was either being sent or received.

Since Outlook wasn't opened, I wonder how do I fine out whether that
mail was sent or received?

How can you know mail sending or receiving was in progress without Outlook
being opened? Did you check Task manager to make sure OUTLOOK.EXE was not
one of the running processes?
--
Brian Tillman