Integration with Outlook - questions from a newbie - sender address

I understand that each user can have only one email address attached to, and only the person who set up an integration can use it or edit it. If I set up a button column, which will send an Outlook email to the client, does that mean that when a team member clicks on the button, they could be sending that email from another team member’s email account? Or is it sent from the email account of the team member who presses the button?

We have a generic email address (email group) that we use, such as This email address is not an Outlook username, it is just an email group. Am I correct that we cannot use that address as the sender address?