Although I'm not familiar with the web version of Outlook.com, in order change the "From" field on the installed version of Outlook, you simply log in to the computer as a different user. Once that's done, the new credentials are used for the sent email.
And yes, I know it's not all that user friendly, but it should work.
Hope this helps.
Grif
I have an email account on outlook.com that I have had for a long time. I just registered a domain for my business on hover.com. I want to continue using the outlook.com email, because I have so many emails stored there. But I want to be able to change the "from" field depending on whether I am sending personal email or business email. The setup menu on outlook.com gives me two options, either use the hover server and people will not see the outlook address, or use outlook server and people will see the outlook address.
Is it possible to change the "from" field at the main email interface?

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