How annoying can it be when autocorrect changes your text and you do not discover that until after you sent it? Do you want to disable autocorrect but cant figure out how?
In outlook 2011 go to menu Outlook/preferences/autocorrect: uncheck "replace text as you type"
Other programs have similar options.
But this is not all. Apple have an "overide" in System Preferences/Keyborad/text: uncheck "correct spelling automaticly".
Now you are done disabling spelling autocorrect. It could be a good idea to keep it and just add exceptions. You can do that in outlook 2011 here: