When you send an email from the BirdEase Message Center, it will appear in your recipient's inbox as being from the name of the Event Contact. So, whoever/whatever is the Primary Contact in the Notification Center -> Message Notifications will be the name appearing to be sending the email, and it will be from notifictions@birdeasepro.com.
So, whoever/whatever is the Primary Contact in the Notification Center -> Message Notifications will also be the reply-to email address.