I'm using Outlook 2010 but I think that any solution to this that works on prior versions would still work.
I have 3 accounts. When I click the 'New E-Mail' button or type Ctrl+N I would like the newly created email to start with a background color. This color will alert me to the account that is active so that I don't send email to personal contacts from my business account or vice versa.
I found several threads for replacing the 'New E-Mail' button with a Macro trigger but I am hoping this can be done with just stationery or sig or a VBA hook of the existing click.