The Blacklists Tab appears on the Mailbox Properties dialog and is used to control which senders may send mail to this mailbox.
Essentially, sender control is based on a blacklist (list of senders from which mail is refused) and a whitelist (list of senders from which mail is accepted). If a sender is in both the blacklist and whitelist, the whitelist takes precedence. Also, the whitelist overrides any decision made by the Anti-Spam system (see the Anti-Spam tab).
Sender Black Lists
Every sender can be considered blacklisted by default, in which case they must also be whitelisted in order to send to this mailbox. This is useful in order to, for example, limit the senders to names that appear in your address book.
In the text area you can enter a list of e-mail addresses that mail will always be accepted from. These addresses are matched to the return-path of the incoming messages. Normally, the return-path is the same as the message author but sometimes (such as for mailing lists) this return-path represents the agent that sent the message (the mailing list itself).
Like most address lists in the system, wildcards can be used.
Accept mail from blacklisted sender, but move to
If this option is checked, then the system will accept mail from a blacklisted sender instead of rejecting the message or issuing a delivery failure notice. However, the message will be stored in the selected folder of this mailbox.
Sender White Lists
In the text area you can list a number of addresses to whitelist, one on each line. You can also use wildcards. These addresses are matched to the message return-path, and any message that matches this list will not be assessed by the anti-spam system (if this function is available on your system).
If you check Whitelist local domains, then any sender address that matches either the primary system domain or one of the aliases will be whitelisted.
If you check Whitelist global/owner's personal address books, then an address will be considered whitelisted if it is the primary e-mail contact address for any contact that exists in either the global address book, or the personal address book belonging to the mailbox owner.