(extracted from another discussion elsewhere)
White/blacklisting is a mail client rule, so only kicks in if the mail is picked
up through the webmail interface and will override the blocking lists. The
blocking lists are a server rule, so are applied regardless of how you obtain
your mail (unless overridden by a whilelist rule in the webmail interface).

If you POP, IMAP or forward SC mail, only the blocking list rules apply. If
mail is picked up through webmail, the user defined filter rules also are
applied and are applied first.

(Deputy) Richard

(extracted from another discussion elsewhere)
That quote is not true. White/black listing is server based. The original quote should have been the additional filters are client based. These are filters the user can create to move messages around between the various folders on the server.

Steven P. Underwood, DNRC
Whitinsville, MA
StevenU[at]POBoxes.com