Your description is a bit confusing, but I'll try...
Company mail as opposed to personal mail???
Sounds like two different mail accounts. Is that correct?
You can set up Outlook to receive multiple email
accounts, but you'll have to choose one to be the default
account. The default account will be the one you Send
from.
Tools - Email accounts - Add a new email account
If I miss-understood you question, try again.
P.S.
I kept my ATT account, backing it down to a $5.95
account. I got DSL through SBC. ATT wasn't marketing
DSL in my area when we moved here, but they are now. I
still use ATT as my primary email account, but access ATT
through SBC.