Mail is not letting me view emails

Do you mean you don't see the Preview Pane and you have Show Side Preview selected in the View menu?

If that is the case, hover your cursor over the right edge of the window and look for the cursor to change to a vertical bar with left arrow. Click and drag to the left way longer than you think should be necessary. About the time you get about ⅔ across the window, it should appear.

thats not what i ment

And this has certainly cleared that up.