Whitehosting is a method of whitelisting that uses the sending servers hostname to define the messages as being whitelisted. Any message from a whitehosted server will be treated as if its sender is whitelisted.
The hostname applies only to messages received via SMTP and uses the text string sent in the EHLO/HELO command. The string is entered into the filter whitelist using Pattern matching characters: The characters * and ? when used in an address or string. e.g. *@domain.com, bob@domian.*, etc.
See: Whitelisting, Filter Whitelist