Please refer to below how to add Trusted Sender (Email or Domain) in Smartermail v16
1. Login to the web interface as administrator through URL : mail.yourdomainname.com and administrator user name with password.
2. Click Settings icon> Domain Settings
3. Select Spam Filtering
Refer Red to add trusted domain, refer Yellow to add trusted sender.
Add in domain name (eg: exabytes.com) under Trusted domain.
Add sender email (eg: [email protected]) under Trusted Email Address.
5. Upon added, click on ok.