Why verify your domain? The primary reason for OwnerRez users is that your email address will also be verified. Once your domain has been verified, any emails associated with it are automatically verified.
If you own your own domain, say acmevacations.com, you can set DNS records that verify us as a sending server. Once you do that, we'll switch to sending directly FROM your verified email address to your verified email domain, such as bookings@acmevacations.com.