Problem
An Evolution user can apparently connect to a mail server, apparently download mail, but sees nothing. As in: there is no list of email in the main pane, just an empty frame.
Possible Solution
Check to see if the "Preview" window is enabled. If so, disable it. If you get your list of email back, it means someone accidentally expanded the preview pane to cover the whole list pane. And when you connect to an email server, by default no messages are selected; no messages means nothing to display in the Preview pane.
You can resize it by re-enabling the preview pane, then grabbing the top of the frame and dragging it down to reveal the list of email.
Commentary
Another instance where an open source tool is excessively flexible. Outlook does not permit you to cover the list frame with the preview frame, it always seems to show a minimum of three lines and cannot be covered any more.
In this case, the user wondered for two weeks just what he'd done.