The from address relates to the account from which the message is sent, so you can create a macro to create a message using your template with the account selected. See the code example in the thread -
https://www.msofficeforums.com/outlo...es-so-box.html
If you don't know how to use code listings - see
http://www.gmayor.com/installing_macro.htm . This uses Word as the vehicle to work with, but Outlook is virtually the same with respect to dialogs etc.