Hello... I have a client that asked if it was possible to deny all incoming emails for a specific email address and or domain unless they are on a white list so to speak. And then have a way where he can modify this list easily. Thanks.. Have a great day!
Never tried such a setup, but it might be possible by using the white- and blacklists of the mail module. But I guess only the admin can use this and only the spamfilter white-/ blacklist is account specific, the postfix ones are server wide. So he might need a dedicated ispconfig server for that.