Changing the Sent Address in Mail App

Hi, I have been recently using a university account (Microsoft) in my mac Mail App. The account has two associated email addresses - a primary one, with the account username (mostly random digits) as the email address, and a secondary one with my name in the email address. Any email sent to either is redirected to the same inbox automatically.

I want to ensure that if I am sending an email from this account, the email is sent from the secondary email address. However the Mail app does not allow me to add the secondary email address - it adds the Exchange account directly, and as a result adds the primary email address only.

If I use Outlook, this problem is not there, as by default an email is sent from the secondary email address. Outlook recognized both the email ids when I added the Microsoft Exchange account.

Any idea how to fix this in the Mail app?

Thanks!