This article explains how to send an email with any From address in Outlook for Office 365, Outlook 2019, 2016, 2013, and 2010.
How can I send an email to multiple recipients separately from Microsoft Outlook?
When you create a new message in Outlook, the email address you use to sign in to Outlook appears in the From field. If you have multiple email accounts and want to use an email address that isn't associated with the account you have open in Outlook, edit the From field of the message and enter the email address you want.
To use an email address in the From field of a message you compose in Outlook:
Start a new message, reply to the message, or forward it in Outlook.
