In box and searching problems

I have 1438 messages in my inbox. When scrolling it I can only see a very small portion of them. Most of them have information that I need. When I attempt to search that box for a particular message, I can not get any results. The failure is apparently do to the fact that I can’t see or read all of the 1438 messages in the box. All boxes were imported from ThunderbirdWhat am I doing wrong? I am new to eM Cliebt. OPlease help me as I am getting despirate.

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