I'm not sure you have spell checking turned on. If not, realize that you need to click Tools / Options, then click on the Spell Checking tab and make sure you have the box 'Check spellling on all messages' (or some such) checked. Read the rest of the options on that tab and configure them to suit your taste, then you'll be able to keep your spelling in line.
<font color=green>****</font color=green> Never Assume <font color=red>ANYTHING</font color=red> <font color=green>****</font color=green>