In Outlook, if you go to Tools->Accounts, and go to the Mail tab (you should be in there by default), you will see a list of your accounts. Click on one, and then click on 'Set as Default'. What this does is set it as the account that you will always be sending from.
Also, when you are sending a mail, and are about to send it, you click on the little pull down arrow on the 'send' button, which will show you your accounts, here you can select which one you will be sending from....Then the next time you are sending a mail, it will still be your default account that you are sending from.
NOTE: Depending on how you have Outlook set up, ie, for home or work or whatever, you might have an option to view a From field......When composing a mail, go to View->From Field. In this field you can choose who you are sending from. Jay~
My new Tae Kwon Do website is up and running!!
~KeyTech