You must be an Administrator to enable this feature.
Start by going to the Company Settings Menu and click on Manage Users. If the person is already a user in the platform, you will see a "Request" button next to them to Send From.
Upon clicking this button, we will e-mail them a request to confirm they're OK with you doing this. The user would need to click the Approve button to allow access to using their email account for outbound emails.
Once approved, you can use this email for sending newsletters and/or setting up as the reply to address.