If your company uses e-mail address not linked to a user such as donotreply@yourcompanyname.com, there is an “Unknown Sender Address” setting under the Web Interface > System > Outbound Control tab. By default it is set to “Reject Message”. If it is set to “Allow Message”, the Sendio ESP will accept outbound e-mail from unknown senders such as donotreply@yourdomain.com. For more information, please refer to the Administration Manual.