Whitelist

Whitelisting allows you to prevent certain filters from being applied to incoming e-mails, thus allowing them to arrive directly in your mailbox. When adding a new Whitelist rule for a specific sending e-mail address or domain, you have the option for disabling the Spam filter only while leaving the Virus filter enabled.

The Whitelist can be applied by two levels of management: the Administrator and the User

The User applied preference always overrides the Administrator set preference. If there is no User defined preference, the Administrator one takes full effect. If for your domain, the Administrator decides to blacklist the domain gmail.com but a User creates a Whitelist rule for that domain, e-mails from gmail.com will be received without problem by that user