Login to Spam filter
URL: https://secure.hostmailserver.com
Username: Email Address
Password: XXXXXXXXXXXX

Once you are logged in Click on the Manage White/Black List Option

If you wish to White list any email address/Domain Name, Just add the desired information in White list Tab and click on save.
Similarly, If you wish to Black list any email address/Domain Name, Just add the desired information in Black list Tab and click on save.

While white listing /Black listing any email address (Example: abc@domain.com) Type the complete email address and click on Save.

While white listing /Black listing any Domain name, Type Domain Name starting with ‘@’ sign (Example: @domain.com) and click on Save.

Note: If Domain is added without “@” it will save but will not be functional.