However, with the Mail app on Windows 10, although you can still add several accounts, clicking the New mail button opens a fly-out menu specifying the account from which you will send the message.
Changing Address Information
If you’ve set up an account through Microsoft 365 or Microsoft Exchange, the server governs all information about the account, including your name and email address. If you’ve selected an IMAP account, however, you enjoy greater control over specifying the display name of the message.
Adjust your display name for IMAP accounts by going to Settings > Manage accounts. Select the relevant account and modify the information as needed.
