A program or set of programs designed to keep unauthorized users or messages from accessing a private network. The firewall usually has rules or protocols that authorize or prohibit outside users or messages. In email, a firewall can be designed so thast messages from domains or users listed as suspect because of spamming, hacking or forging will not be delivered.

Building an Opt-In List, Building Relationships
If you aim for success, you must do everything within your means to achieve that. You just donÃt go on sitting there in your house complaining about not getting as much profit as you expect.