Curtis: > What I'd prefer to do here is have the bounces held for customer review so > that they can realize that they've got an email address that isn't > delivering and fix the problem on their end.
Sorry, that does not work. Even my two-user domain sometimes gets thousands of email messages a day for non-existent recipients. No-one is going to review such garbage for mis-directed legitimate mail. Companies that provide out-sourced email filtering service often don't have up-to-date recipient lists. Instead they verify addresses in real-time. The Postfix implementation of this is described in http://www.postfix.org/ADDRESS_VERIFICATION_README.html. It supports routing overrides, positive caching and negative caching. Wietse
