Problem with Mail

I have a problem with MAIL it will not open when I select Mail from dock the Mail page opens but when i try to select anything or after a secound the cursor changes to a Beach ball and freezes all options on page even if leave it for a couple of hours its still revolving.
Al I can do is to select mail in the dock and force quit to close mail. I have had a few messages saying my starter disk is nearly full if that helps but as I am new to Macs have no Idea how to solve the error I do not get any other messages than the one mentioned . would appreciate any help from the team Many thanks
Jimmysplan Not-Amused:

First, how much space do you have left on your HDD? Select it, and use Get info from the menu bar.

I send e-mails to a friend of mine and he keeps getting them in his Junk mail. Is there anyone that knows how to take care of this problem? He is trying to fix it to where my e-mails are going to his In box.