Outlook - Choose which e-mail account to use to send a message
I'm always forgetting how to change my account on the fly sending email in Outlook, so I'm putting this here to remind myself in the future, hopefully it will help others too
If you set up multiple e-mail accounts in Microsoft Outlook, you can choose which account to use when you send a message.
In the message window, click Account.
Click the account that you want to use.