What will happen with your email is entirely dependent on how your email provider’s SMTP server is configured. The client simply sends the email to your provider’s SMTP server (Simple Mail Transfer Protocol server, often called a mail server), and lets the SMTP server decide what to do with your email. Microsoft Outlook itself, and other email clients like Thunderbird or Apple Mail, don’t do any checking on the email address from which you send. How Email Providers Handle Messages Sent From a Different “From” Address
Both of those answers are dependent on who your email provider is.
